/*
 * Copyright (c) 2006 Luc Verhaegen (quirks list)
 * Copyright (c) 2007-2008 Intel Corporation
 *   Jesse Barnes <jesse.barnes@intel.com>
 * Copyright 2010 Red Hat, Inc.
 *
 * DDC probing routines (drm_ddc_read & drm_do_probe_ddc_edid) originally from
 * FB layer.
 *   Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <sys/cdefs.h>
#include <dev/drm2/drmP.h>
#include <dev/drm2/drm_edid.h>
#include "drm_edid_modes.h"
#include <dev/iicbus/iic.h>
#include <dev/iicbus/iiconf.h>
#include "iicbus_if.h"

#define version_greater(edid, maj, min) \
        (((edid)->version > (maj)) || \
         ((edid)->version == (maj) && (edid)->revision > (min)))

#define EDID_EST_TIMINGS 16
#define EDID_STD_TIMINGS 8
#define EDID_DETAILED_TIMINGS 4

/*
 * EDID blocks out in the wild have a variety of bugs, try to collect
 * them here (note that userspace may work around broken monitors first,
 * but fixes should make their way here so that the kernel "just works"
 * on as many displays as possible).
 */

/* First detailed mode wrong, use largest 60Hz mode */
#define EDID_QUIRK_PREFER_LARGE_60              (1 << 0)
/* Reported 135MHz pixel clock is too high, needs adjustment */
#define EDID_QUIRK_135_CLOCK_TOO_HIGH           (1 << 1)
/* Prefer the largest mode at 75 Hz */
#define EDID_QUIRK_PREFER_LARGE_75              (1 << 2)
/* Detail timing is in cm not mm */
#define EDID_QUIRK_DETAILED_IN_CM               (1 << 3)
/* Detailed timing descriptors have bogus size values, so just take the
 * maximum size and use that.
 */
#define EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE    (1 << 4)
/* Monitor forgot to set the first detailed is preferred bit. */
#define EDID_QUIRK_FIRST_DETAILED_PREFERRED     (1 << 5)
/* use +hsync +vsync for detailed mode */
#define EDID_QUIRK_DETAILED_SYNC_PP             (1 << 6)
/* Force reduced-blanking timings for detailed modes */
#define EDID_QUIRK_FORCE_REDUCED_BLANKING       (1 << 7)

struct detailed_mode_closure {
        struct drm_connector *connector;
        struct edid *edid;
        bool preferred;
        u32 quirks;
        int modes;
};

#define LEVEL_DMT       0
#define LEVEL_GTF       1
#define LEVEL_GTF2      2
#define LEVEL_CVT       3

static struct edid_quirk {
        char vendor[4];
        int product_id;
        u32 quirks;
} edid_quirk_list[] = {
        /* Acer AL1706 */
        { "ACR", 44358, EDID_QUIRK_PREFER_LARGE_60 },
        /* Acer F51 */
        { "API", 0x7602, EDID_QUIRK_PREFER_LARGE_60 },
        /* Unknown Acer */
        { "ACR", 2423, EDID_QUIRK_FIRST_DETAILED_PREFERRED },

        /* Belinea 10 15 55 */
        { "MAX", 1516, EDID_QUIRK_PREFER_LARGE_60 },
        { "MAX", 0x77e, EDID_QUIRK_PREFER_LARGE_60 },

        /* Envision Peripherals, Inc. EN-7100e */
        { "EPI", 59264, EDID_QUIRK_135_CLOCK_TOO_HIGH },
        /* Envision EN2028 */
        { "EPI", 8232, EDID_QUIRK_PREFER_LARGE_60 },

        /* Funai Electronics PM36B */
        { "FCM", 13600, EDID_QUIRK_PREFER_LARGE_75 |
          EDID_QUIRK_DETAILED_IN_CM },

        /* LG Philips LCD LP154W01-A5 */
        { "LPL", 0, EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE },
        { "LPL", 0x2a00, EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE },

        /* Philips 107p5 CRT */
        { "PHL", 57364, EDID_QUIRK_FIRST_DETAILED_PREFERRED },

        /* Proview AY765C */
        { "PTS", 765, EDID_QUIRK_FIRST_DETAILED_PREFERRED },

        /* Samsung SyncMaster 205BW.  Note: irony */
        { "SAM", 541, EDID_QUIRK_DETAILED_SYNC_PP },
        /* Samsung SyncMaster 22[5-6]BW */
        { "SAM", 596, EDID_QUIRK_PREFER_LARGE_60 },
        { "SAM", 638, EDID_QUIRK_PREFER_LARGE_60 },

        /* ViewSonic VA2026w */
        { "VSC", 5020, EDID_QUIRK_FORCE_REDUCED_BLANKING },
};

/*** DDC fetch and block validation ***/

static const u8 edid_header[] = {
        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00
};

 /*
 * Sanity check the header of the base EDID block.  Return 8 if the header
 * is perfect, down to 0 if it's totally wrong.
 */
int drm_edid_header_is_valid(const u8 *raw_edid)
{
        int i, score = 0;

        for (i = 0; i < sizeof(edid_header); i++)
                if (raw_edid[i] == edid_header[i])
                        score++;

        return score;
}
EXPORT_SYMBOL(drm_edid_header_is_valid);

static int edid_fixup __read_mostly = 6;
module_param_named(edid_fixup, edid_fixup, int, 0400);
MODULE_PARM_DESC(edid_fixup,
                 "Minimum number of valid EDID header bytes (0-8, default 6)");

/*
 * Sanity check the EDID block (base or extension).  Return 0 if the block
 * doesn't check out, or 1 if it's valid.
 */
bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid)
{
        int i;
        u8 csum = 0;
        struct edid *edid = (struct edid *)raw_edid;

        if (edid_fixup > 8 || edid_fixup < 0)
                edid_fixup = 6;

        if (block == 0) {
                int score = drm_edid_header_is_valid(raw_edid);
                if (score == 8) ;
                else if (score >= edid_fixup) {
                        DRM_DEBUG("Fixing EDID header, your hardware may be failing\n");
                        memcpy(raw_edid, edid_header, sizeof(edid_header));
                } else {
                        goto bad;
                }
        }

        for (i = 0; i < EDID_LENGTH; i++)
                csum += raw_edid[i];
        if (csum) {
                if (print_bad_edid) {
                        DRM_ERROR("EDID checksum is invalid, remainder is %d\n", csum);
                }

                /* allow CEA to slide through, switches mangle this */
                if (raw_edid[0] != 0x02)
                        goto bad;
        }

        /* per-block-type checks */
        switch (raw_edid[0]) {
        case 0: /* base */
                if (edid->version != 1) {
                        DRM_ERROR("EDID has major version %d, instead of 1\n", edid->version);
                        goto bad;
                }

                if (edid->revision > 4)
                        DRM_DEBUG("EDID minor > 4, assuming backward compatibility\n");
                break;

        default:
                break;
        }

        return 1;

bad:
        if (raw_edid && print_bad_edid) {
                DRM_DEBUG_KMS("Raw EDID:\n");
                for (i = 0; i < EDID_LENGTH; ) {
                        printf("%02x", raw_edid[i]);
                        i++;
                        if (i % 16 == 0 || i == EDID_LENGTH)
                                printf("\n");
                        else if (i % 8 == 0)
                                printf("  ");
                        else
                                printf(" ");
                }
        }
        return 0;
}
EXPORT_SYMBOL(drm_edid_block_valid);

/**
 * drm_edid_is_valid - sanity check EDID data
 * @edid: EDID data
 *
 * Sanity-check an entire EDID record (including extensions)
 */
bool drm_edid_is_valid(struct edid *edid)
{
        int i;
        u8 *raw = (u8 *)edid;

        if (!edid)
                return false;

        for (i = 0; i <= edid->extensions; i++)
                if (!drm_edid_block_valid(raw + i * EDID_LENGTH, i, true))
                        return false;

        return true;
}
EXPORT_SYMBOL(drm_edid_is_valid);

#define DDC_SEGMENT_ADDR 0x30
/**
 * Get EDID information via I2C.
 *
 * \param adapter : i2c device adaptor
 * \param buf     : EDID data buffer to be filled
 * \param len     : EDID data buffer length
 * \return 0 on success or -1 on failure.
 *
 * Try to fetch EDID information by calling i2c driver function.
 */
static int
drm_do_probe_ddc_edid(device_t adapter, unsigned char *buf,
                      int block, int len)
{
        unsigned char start = block * EDID_LENGTH;
        unsigned char segment = block >> 1;
        unsigned char xfers = segment ? 3 : 2;
        int ret, retries = 5;

        /* The core i2c driver will automatically retry the transfer if the
         * adapter reports EAGAIN. However, we find that bit-banging transfers
         * are susceptible to errors under a heavily loaded machine and
         * generate spurious NAKs and timeouts. Retrying the transfer
         * of the individual block a few times seems to overcome this.
         */
        do {
                struct iic_msg msgs[] = {
                        {
                                .slave  = DDC_SEGMENT_ADDR << 1,
                                .flags  = 0,
                                .len    = 1,
                                .buf    = &segment,
                        }, {
                                .slave  = DDC_ADDR << 1,
                                .flags  = 0,
                                .len    = 1,
                                .buf    = &start,
                        }, {
                                .slave  = DDC_ADDR << 1,
                                .flags  = IIC_M_RD,
                                .len    = len,
                                .buf    = buf,
                        }
                };

        /*
         * Avoid sending the segment addr to not upset non-compliant ddc
         * monitors.
         */
                ret = iicbus_transfer(adapter, &msgs[3 - xfers], xfers);

                if (ret != 0)
                        DRM_DEBUG_KMS("iicbus_transfer countdown %d error %d\n",
                            retries, ret);
        } while (ret != 0 && --retries);

        return ret == 0 ? 0 : -1;
}

static bool drm_edid_is_zero(u8 *in_edid, int length)
{
        int i;
        u32 *raw_edid = (u32 *)in_edid;

        for (i = 0; i < length / 4; i++)
                if (*(raw_edid + i) != 0)
                        return false;

        return true;
}

static u8 *
drm_do_get_edid(struct drm_connector *connector, device_t adapter)
{
        int i, j = 0, valid_extensions = 0;
        u8 *block, *new;
        bool print_bad_edid = !connector->bad_edid_counter || (drm_debug & DRM_DEBUGBITS_KMS);

        if ((block = malloc(EDID_LENGTH, DRM_MEM_KMS, M_NOWAIT)) == NULL)
                return NULL;

        /* base block fetch */
        for (i = 0; i < 4; i++) {
                if (drm_do_probe_ddc_edid(adapter, block, 0, EDID_LENGTH))
                        goto out;
                if (drm_edid_block_valid(block, 0, print_bad_edid))
                        break;
                if (i == 0 && drm_edid_is_zero(block, EDID_LENGTH)) {
                        connector->null_edid_counter++;
                        goto carp;
                }
        }
        if (i == 4)
                goto carp;

        /* if there's no extensions, we're done */
        if (block[0x7e] == 0)
                return block;

        new = reallocf(block, (block[0x7e] + 1) * EDID_LENGTH, DRM_MEM_KMS,
            M_NOWAIT);
        if (!new) {
                block = NULL;
                goto out;
        }
        block = new;

        for (j = 1; j <= block[0x7e]; j++) {
                for (i = 0; i < 4; i++) {
                        if (drm_do_probe_ddc_edid(adapter,
                                  block + (valid_extensions + 1) * EDID_LENGTH,
                                  j, EDID_LENGTH))
                                goto out;
                        if (drm_edid_block_valid(block + (valid_extensions + 1) * EDID_LENGTH, j, print_bad_edid)) {
                                valid_extensions++;
                                break;
                        }
                }

                if (i == 4 && print_bad_edid) {
                        dev_warn(connector->dev->dev,
                         "%s: Ignoring invalid EDID block %d.\n",
                         drm_get_connector_name(connector), j);

                        connector->bad_edid_counter++;
                }
        }

        if (valid_extensions != block[0x7e]) {
                block[EDID_LENGTH-1] += block[0x7e] - valid_extensions;
                block[0x7e] = valid_extensions;
                new = reallocf(block, (valid_extensions + 1) * EDID_LENGTH,
                    DRM_MEM_KMS, M_NOWAIT);
                if (!new)
                        goto out;
                block = new;
        }

        return block;

carp:
        if (print_bad_edid) {
                dev_warn(connector->dev->dev, "%s: EDID block %d invalid.\n",
                         drm_get_connector_name(connector), j);
        }
        connector->bad_edid_counter++;

out:
        free(block, DRM_MEM_KMS);
        return NULL;
}

/**
 * Probe DDC presence.
 *
 * \param adapter : i2c device adaptor
 * \return 1 on success
 */
bool
drm_probe_ddc(device_t adapter)
{
        unsigned char out;

        return (drm_do_probe_ddc_edid(adapter, &out, 0, 1) == 0);
}
EXPORT_SYMBOL(drm_probe_ddc);

/**
 * drm_get_edid - get EDID data, if available
 * @connector: connector we're probing
 * @adapter: i2c adapter to use for DDC
 *
 * Poke the given i2c channel to grab EDID data if possible.  If found,
 * attach it to the connector.
 *
 * Return edid data or NULL if we couldn't find any.
 */
struct edid *drm_get_edid(struct drm_connector *connector,
                          device_t adapter)
{
        struct edid *edid = NULL;

        if (drm_probe_ddc(adapter))
                edid = (struct edid *)drm_do_get_edid(connector, adapter);

        return edid;
}
EXPORT_SYMBOL(drm_get_edid);

/*** EDID parsing ***/

/**
 * edid_vendor - match a string against EDID's obfuscated vendor field
 * @edid: EDID to match
 * @vendor: vendor string
 *
 * Returns true if @vendor is in @edid, false otherwise
 */
static bool edid_vendor(struct edid *edid, char *vendor)
{
        char edid_vendor[3];

        edid_vendor[0] = ((edid->mfg_id[0] & 0x7c) >> 2) + '@';
        edid_vendor[1] = (((edid->mfg_id[0] & 0x3) << 3) |
                          ((edid->mfg_id[1] & 0xe0) >> 5)) + '@';
        edid_vendor[2] = (edid->mfg_id[1] & 0x1f) + '@';

        return !strncmp(edid_vendor, vendor, 3);
}

/**
 * edid_get_quirks - return quirk flags for a given EDID
 * @edid: EDID to process
 *
 * This tells subsequent routines what fixes they need to apply.
 */
static u32 edid_get_quirks(struct edid *edid)
{
        struct edid_quirk *quirk;
        int i;

        for (i = 0; i < ARRAY_SIZE(edid_quirk_list); i++) {
                quirk = &edid_quirk_list[i];

                if (edid_vendor(edid, quirk->vendor) &&
                    (EDID_PRODUCT_ID(edid) == quirk->product_id))
                        return quirk->quirks;
        }

        return 0;
}

#define MODE_SIZE(m) ((m)->hdisplay * (m)->vdisplay)
#define MODE_REFRESH_DIFF(m,r) (abs((m)->vrefresh - target_refresh))

/**
 * edid_fixup_preferred - set preferred modes based on quirk list
 * @connector: has mode list to fix up
 * @quirks: quirks list
 *
 * Walk the mode list for @connector, clearing the preferred status
 * on existing modes and setting it anew for the right mode ala @quirks.
 */
static void edid_fixup_preferred(struct drm_connector *connector,
                                 u32 quirks)
{
        struct drm_display_mode *t, *cur_mode, *preferred_mode;
        int target_refresh = 0;

        if (list_empty(&connector->probed_modes))
                return;

        if (quirks & EDID_QUIRK_PREFER_LARGE_60)
                target_refresh = 60;
        if (quirks & EDID_QUIRK_PREFER_LARGE_75)
                target_refresh = 75;

        preferred_mode = list_first_entry(&connector->probed_modes,
                                          struct drm_display_mode, head);

        list_for_each_entry_safe(cur_mode, t, &connector->probed_modes, head) {
                cur_mode->type &= ~DRM_MODE_TYPE_PREFERRED;

                if (cur_mode == preferred_mode)
                        continue;

                /* Largest mode is preferred */
                if (MODE_SIZE(cur_mode) > MODE_SIZE(preferred_mode))
                        preferred_mode = cur_mode;

                /* At a given size, try to get closest to target refresh */
                if ((MODE_SIZE(cur_mode) == MODE_SIZE(preferred_mode)) &&
                    MODE_REFRESH_DIFF(cur_mode, target_refresh) <
                    MODE_REFRESH_DIFF(preferred_mode, target_refresh)) {
                        preferred_mode = cur_mode;
                }
        }

        preferred_mode->type |= DRM_MODE_TYPE_PREFERRED;
}

static bool
mode_is_rb(const struct drm_display_mode *mode)
{
        return (mode->htotal - mode->hdisplay == 160) &&
               (mode->hsync_end - mode->hdisplay == 80) &&
               (mode->hsync_end - mode->hsync_start == 32) &&
               (mode->vsync_start - mode->vdisplay == 3);
}

/*
 * drm_mode_find_dmt - Create a copy of a mode if present in DMT
 * @dev: Device to duplicate against
 * @hsize: Mode width
 * @vsize: Mode height
 * @fresh: Mode refresh rate
 * @rb: Mode reduced-blanking-ness
 *
 * Walk the DMT mode list looking for a match for the given parameters.
 * Return a newly allocated copy of the mode, or NULL if not found.
 */
struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
                                           int hsize, int vsize, int fresh,
                                           bool rb)
{
        int i;

        for (i = 0; i < drm_num_dmt_modes; i++) {
                const struct drm_display_mode *ptr = &drm_dmt_modes[i];
                if (hsize != ptr->hdisplay)
                        continue;
                if (vsize != ptr->vdisplay)
                        continue;
                if (fresh != drm_mode_vrefresh(ptr))
                        continue;
                if (rb != mode_is_rb(ptr))
                        continue;

                return drm_mode_duplicate(dev, ptr);
        }

        return NULL;
}
EXPORT_SYMBOL(drm_mode_find_dmt);

typedef void detailed_cb(struct detailed_timing *timing, void *closure);

static void
cea_for_each_detailed_block(u8 *ext, detailed_cb *cb, void *closure)
{
        int i, n = 0;
        u8 d = ext[0x02];
        u8 *det_base = ext + d;

        n = (127 - d) / 18;
        for (i = 0; i < n; i++)
                cb((struct detailed_timing *)(det_base + 18 * i), closure);
}

static void
vtb_for_each_detailed_block(u8 *ext, detailed_cb *cb, void *closure)
{
        unsigned int i, n = min((int)ext[0x02], 6);
        u8 *det_base = ext + 5;

        if (ext[0x01] != 1)
                return; /* unknown version */

        for (i = 0; i < n; i++)
                cb((struct detailed_timing *)(det_base + 18 * i), closure);
}

static void
drm_for_each_detailed_block(u8 *raw_edid, detailed_cb *cb, void *closure)
{
        int i;
        struct edid *edid = (struct edid *)raw_edid;

        if (edid == NULL)
                return;

        for (i = 0; i < EDID_DETAILED_TIMINGS; i++)
                cb(&(edid->detailed_timings[i]), closure);

        for (i = 1; i <= raw_edid[0x7e]; i++) {
                u8 *ext = raw_edid + (i * EDID_LENGTH);
                switch (*ext) {
                case CEA_EXT:
                        cea_for_each_detailed_block(ext, cb, closure);
                        break;
                case VTB_EXT:
                        vtb_for_each_detailed_block(ext, cb, closure);
                        break;
                default:
                        break;
                }
        }
}

static void
is_rb(struct detailed_timing *t, void *data)
{
        u8 *r = (u8 *)t;
        if (r[3] == EDID_DETAIL_MONITOR_RANGE)
                if (r[15] & 0x10)
                        *(bool *)data = true;
}

/* EDID 1.4 defines this explicitly.  For EDID 1.3, we guess, badly. */
static bool
drm_monitor_supports_rb(struct edid *edid)
{
        if (edid->revision >= 4) {
                bool ret = false;
                drm_for_each_detailed_block((u8 *)edid, is_rb, &ret);
                return ret;
        }

        return ((edid->input & DRM_EDID_INPUT_DIGITAL) != 0);
}

static void
find_gtf2(struct detailed_timing *t, void *data)
{
        u8 *r = (u8 *)t;
        if (r[3] == EDID_DETAIL_MONITOR_RANGE && r[10] == 0x02)
                *(u8 **)data = r;
}

/* Secondary GTF curve kicks in above some break frequency */
static int
drm_gtf2_hbreak(struct edid *edid)
{
        u8 *r = NULL;
        drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
        return r ? (r[12] * 2) : 0;
}

static int
drm_gtf2_2c(struct edid *edid)
{
        u8 *r = NULL;
        drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
        return r ? r[13] : 0;
}

static int
drm_gtf2_m(struct edid *edid)
{
        u8 *r = NULL;
        drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
        return r ? (r[15] << 8) + r[14] : 0;
}

static int
drm_gtf2_k(struct edid *edid)
{
        u8 *r = NULL;
        drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
        return r ? r[16] : 0;
}

static int
drm_gtf2_2j(struct edid *edid)
{
        u8 *r = NULL;
        drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
        return r ? r[17] : 0;
}

/**
 * standard_timing_level - get std. timing level(CVT/GTF/DMT)
 * @edid: EDID block to scan
 */
static int standard_timing_level(struct edid *edid)
{
        if (edid->revision >= 2) {
                if (edid->revision >= 4 && (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF))
                        return LEVEL_CVT;
                if (drm_gtf2_hbreak(edid))
                        return LEVEL_GTF2;
                return LEVEL_GTF;
        }
        return LEVEL_DMT;
}

/*
 * 0 is reserved.  The spec says 0x01 fill for unused timings.  Some old
 * monitors fill with ascii space (0x20) instead.
 */
static int
bad_std_timing(u8 a, u8 b)
{
        return (a == 0x00 && b == 0x00) ||
               (a == 0x01 && b == 0x01) ||
               (a == 0x20 && b == 0x20);
}

/**
 * drm_mode_std - convert standard mode info (width, height, refresh) into mode
 * @t: standard timing params
 * @timing_level: standard timing level
 *
 * Take the standard timing params (in this case width, aspect, and refresh)
 * and convert them into a real mode using CVT/GTF/DMT.
 */
static struct drm_display_mode *
drm_mode_std(struct drm_connector *connector, struct edid *edid,
             struct std_timing *t, int revision)
{
        struct drm_device *dev = connector->dev;
        struct drm_display_mode *m, *mode = NULL;
        int hsize, vsize;
        int vrefresh_rate;
        unsigned aspect_ratio = (t->vfreq_aspect & EDID_TIMING_ASPECT_MASK)
                >> EDID_TIMING_ASPECT_SHIFT;
        unsigned vfreq = (t->vfreq_aspect & EDID_TIMING_VFREQ_MASK)
                >> EDID_TIMING_VFREQ_SHIFT;
        int timing_level = standard_timing_level(edid);

        if (bad_std_timing(t->hsize, t->vfreq_aspect))
                return NULL;

        /* According to the EDID spec, the hdisplay = hsize * 8 + 248 */
        hsize = t->hsize * 8 + 248;
        /* vrefresh_rate = vfreq + 60 */
        vrefresh_rate = vfreq + 60;
        /* the vdisplay is calculated based on the aspect ratio */
        if (aspect_ratio == 0) {
                if (revision < 3)
                        vsize = hsize;
                else
                        vsize = (hsize * 10) / 16;
        } else if (aspect_ratio == 1)
                vsize = (hsize * 3) / 4;
        else if (aspect_ratio == 2)
                vsize = (hsize * 4) / 5;
        else
                vsize = (hsize * 9) / 16;

        /* HDTV hack, part 1 */
        if (vrefresh_rate == 60 &&
            ((hsize == 1360 && vsize == 765) ||
             (hsize == 1368 && vsize == 769))) {
                hsize = 1366;
                vsize = 768;
        }

        /*
         * If this connector already has a mode for this size and refresh
         * rate (because it came from detailed or CVT info), use that
         * instead.  This way we don't have to guess at interlace or
         * reduced blanking.
         */
        list_for_each_entry(m, &connector->probed_modes, head)
                if (m->hdisplay == hsize && m->vdisplay == vsize &&
                    drm_mode_vrefresh(m) == vrefresh_rate)
                        return NULL;

        /* HDTV hack, part 2 */
        if (hsize == 1366 && vsize == 768 && vrefresh_rate == 60) {
                mode = drm_cvt_mode(dev, 1366, 768, vrefresh_rate, 0, 0,
                                    false);
                mode->hdisplay = 1366;
                mode->hsync_start = mode->hsync_start - 1;
                mode->hsync_end = mode->hsync_end - 1;
                return mode;
        }

        /* check whether it can be found in default mode table */
        if (drm_monitor_supports_rb(edid)) {
                mode = drm_mode_find_dmt(dev, hsize, vsize, vrefresh_rate,
                                         true);
                if (mode)
                        return mode;
        }
        mode = drm_mode_find_dmt(dev, hsize, vsize, vrefresh_rate, false);
        if (mode)
                return mode;

        /* okay, generate it */
        switch (timing_level) {
        case LEVEL_DMT:
                break;
        case LEVEL_GTF:
                mode = drm_gtf_mode(dev, hsize, vsize, vrefresh_rate, 0, 0);
                break;
        case LEVEL_GTF2:
                /*
                 * This is potentially wrong if there's ever a monitor with
                 * more than one ranges section, each claiming a different
                 * secondary GTF curve.  Please don't do that.
                 */
                mode = drm_gtf_mode(dev, hsize, vsize, vrefresh_rate, 0, 0);
                if (!mode)
                        return NULL;
                if (drm_mode_hsync(mode) > drm_gtf2_hbreak(edid)) {
                        drm_mode_destroy(dev, mode);
                        mode = drm_gtf_mode_complex(dev, hsize, vsize,
                                                    vrefresh_rate, 0, 0,
                                                    drm_gtf2_m(edid),
                                                    drm_gtf2_2c(edid),
                                                    drm_gtf2_k(edid),
                                                    drm_gtf2_2j(edid));
                }
                break;
        case LEVEL_CVT:
                mode = drm_cvt_mode(dev, hsize, vsize, vrefresh_rate, 0, 0,
                                    false);
                break;
        }
        return mode;
}

/*
 * EDID is delightfully ambiguous about how interlaced modes are to be
 * encoded.  Our internal representation is of frame height, but some
 * HDTV detailed timings are encoded as field height.
 *
 * The format list here is from CEA, in frame size.  Technically we
 * should be checking refresh rate too.  Whatever.
 */
static void
drm_mode_do_interlace_quirk(struct drm_display_mode *mode,
                            struct detailed_pixel_timing *pt)
{
        int i;
        static const struct {
                int w, h;
        } cea_interlaced[] = {
                { 1920, 1080 },
                {  720,  480 },
                { 1440,  480 },
                { 2880,  480 },
                {  720,  576 },
                { 1440,  576 },
                { 2880,  576 },
        };

        if (!(pt->misc & DRM_EDID_PT_INTERLACED))
                return;

        for (i = 0; i < ARRAY_SIZE(cea_interlaced); i++) {
                if ((mode->hdisplay == cea_interlaced[i].w) &&
                    (mode->vdisplay == cea_interlaced[i].h / 2)) {
                        mode->vdisplay *= 2;
                        mode->vsync_start *= 2;
                        mode->vsync_end *= 2;
                        mode->vtotal *= 2;
                        mode->vtotal |= 1;
                }
        }

        mode->flags |= DRM_MODE_FLAG_INTERLACE;
}

/**
 * drm_mode_detailed - create a new mode from an EDID detailed timing section
 * @dev: DRM device (needed to create new mode)
 * @edid: EDID block
 * @timing: EDID detailed timing info
 * @quirks: quirks to apply
 *
 * An EDID detailed timing block contains enough info for us to create and
 * return a new struct drm_display_mode.
 */
static struct drm_display_mode *drm_mode_detailed(struct drm_device *dev,
                                                  struct edid *edid,
                                                  struct detailed_timing *timing,
                                                  u32 quirks)
{
        struct drm_display_mode *mode;
        struct detailed_pixel_timing *pt = &timing->data.pixel_data;
        unsigned hactive = (pt->hactive_hblank_hi & 0xf0) << 4 | pt->hactive_lo;
        unsigned vactive = (pt->vactive_vblank_hi & 0xf0) << 4 | pt->vactive_lo;
        unsigned hblank = (pt->hactive_hblank_hi & 0xf) << 8 | pt->hblank_lo;
        unsigned vblank = (pt->vactive_vblank_hi & 0xf) << 8 | pt->vblank_lo;
        unsigned hsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 0xc0) << 2 | pt->hsync_offset_lo;
        unsigned hsync_pulse_width = (pt->hsync_vsync_offset_pulse_width_hi & 0x30) << 4 | pt->hsync_pulse_width_lo;
        unsigned vsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 0xc) << 2 | pt->vsync_offset_pulse_width_lo >> 4;
        unsigned vsync_pulse_width = (pt->hsync_vsync_offset_pulse_width_hi & 0x3) << 4 | (pt->vsync_offset_pulse_width_lo & 0xf);

        /* ignore tiny modes */
        if (hactive < 64 || vactive < 64)
                return NULL;

        if (pt->misc & DRM_EDID_PT_STEREO) {
                printf("stereo mode not supported\n");
                return NULL;
        }
        if (!(pt->misc & DRM_EDID_PT_SEPARATE_SYNC)) {
                printf("composite sync not supported\n");
        }

        /* it is incorrect if hsync/vsync width is zero */
        if (!hsync_pulse_width || !vsync_pulse_width) {
                DRM_DEBUG_KMS("Incorrect Detailed timing. "
                                "Wrong Hsync/Vsync pulse width\n");
                return NULL;
        }

        if (quirks & EDID_QUIRK_FORCE_REDUCED_BLANKING) {
                mode = drm_cvt_mode(dev, hactive, vactive, 60, true, false, false);
                if (!mode)
                        return NULL;

                goto set_size;
        }

        mode = drm_mode_create(dev);
        if (!mode)
                return NULL;

        if (quirks & EDID_QUIRK_135_CLOCK_TOO_HIGH)
                timing->pixel_clock = cpu_to_le16(1088);

        mode->clock = le16_to_cpu(timing->pixel_clock) * 10;

        mode->hdisplay = hactive;
        mode->hsync_start = mode->hdisplay + hsync_offset;
        mode->hsync_end = mode->hsync_start + hsync_pulse_width;
        mode->htotal = mode->hdisplay + hblank;

        mode->vdisplay = vactive;
        mode->vsync_start = mode->vdisplay + vsync_offset;
        mode->vsync_end = mode->vsync_start + vsync_pulse_width;
        mode->vtotal = mode->vdisplay + vblank;

        /* Some EDIDs have bogus h/vtotal values */
        if (mode->hsync_end > mode->htotal)
                mode->htotal = mode->hsync_end + 1;
        if (mode->vsync_end > mode->vtotal)
                mode->vtotal = mode->vsync_end + 1;

        drm_mode_do_interlace_quirk(mode, pt);

        if (quirks & EDID_QUIRK_DETAILED_SYNC_PP) {
                pt->misc |= DRM_EDID_PT_HSYNC_POSITIVE | DRM_EDID_PT_VSYNC_POSITIVE;
        }

        mode->flags |= (pt->misc & DRM_EDID_PT_HSYNC_POSITIVE) ?
                DRM_MODE_FLAG_PHSYNC : DRM_MODE_FLAG_NHSYNC;
        mode->flags |= (pt->misc & DRM_EDID_PT_VSYNC_POSITIVE) ?
                DRM_MODE_FLAG_PVSYNC : DRM_MODE_FLAG_NVSYNC;

set_size:
        mode->width_mm = pt->width_mm_lo | (pt->width_height_mm_hi & 0xf0) << 4;
        mode->height_mm = pt->height_mm_lo | (pt->width_height_mm_hi & 0xf) << 8;

        if (quirks & EDID_QUIRK_DETAILED_IN_CM) {
                mode->width_mm *= 10;
                mode->height_mm *= 10;
        }

        if (quirks & EDID_QUIRK_DETAILED_USE_MAXIMUM_SIZE) {
                mode->width_mm = edid->width_cm * 10;
                mode->height_mm = edid->height_cm * 10;
        }

        mode->type = DRM_MODE_TYPE_DRIVER;
        mode->vrefresh = drm_mode_vrefresh(mode);
        drm_mode_set_name(mode);

        return mode;
}

static bool
mode_in_hsync_range(const struct drm_display_mode *mode,
                    struct edid *edid, u8 *t)
{
        int hsync, hmin, hmax;

        hmin = t[7];
        if (edid->revision >= 4)
            hmin += ((t[4] & 0x04) ? 255 : 0);
        hmax = t[8];
        if (edid->revision >= 4)
            hmax += ((t[4] & 0x08) ? 255 : 0);
        hsync = drm_mode_hsync(mode);

        return (hsync <= hmax && hsync >= hmin);
}

static bool
mode_in_vsync_range(const struct drm_display_mode *mode,
                    struct edid *edid, u8 *t)
{
        int vsync, vmin, vmax;

        vmin = t[5];
        if (edid->revision >= 4)
            vmin += ((t[4] & 0x01) ? 255 : 0);
        vmax = t[6];
        if (edid->revision >= 4)
            vmax += ((t[4] & 0x02) ? 255 : 0);
        vsync = drm_mode_vrefresh(mode);

        return (vsync <= vmax && vsync >= vmin);
}

static u32
range_pixel_clock(struct edid *edid, u8 *t)
{
        /* unspecified */
        if (t[9] == 0 || t[9] == 255)
                return 0;

        /* 1.4 with CVT support gives us real precision, yay */
        if (edid->revision >= 4 && t[10] == 0x04)
                return (t[9] * 10000) - ((t[12] >> 2) * 250);

        /* 1.3 is pathetic, so fuzz up a bit */
        return t[9] * 10000 + 5001;
}

static bool
mode_in_range(const struct drm_display_mode *mode, struct edid *edid,
              struct detailed_timing *timing)
{
        u32 max_clock;
        u8 *t = (u8 *)timing;

        if (!mode_in_hsync_range(mode, edid, t))
                return false;

        if (!mode_in_vsync_range(mode, edid, t))
                return false;

        if ((max_clock = range_pixel_clock(edid, t)))
                if (mode->clock > max_clock)
                        return false;

        /* 1.4 max horizontal check */
        if (edid->revision >= 4 && t[10] == 0x04)
                if (t[13] && mode->hdisplay > 8 * (t[13] + (256 * (t[12]&0x3))))
                        return false;

        if (mode_is_rb(mode) && !drm_monitor_supports_rb(edid))
                return false;

        return true;
}

static bool valid_inferred_mode(const struct drm_connector *connector,
                                const struct drm_display_mode *mode)
{
        struct drm_display_mode *m;
        bool ok = false;

        list_for_each_entry(m, &connector->probed_modes, head) {
                if (mode->hdisplay == m->hdisplay &&
                    mode->vdisplay == m->vdisplay &&
                    drm_mode_vrefresh(mode) == drm_mode_vrefresh(m))
                        return false; /* duplicated */
                if (mode->hdisplay <= m->hdisplay &&
                    mode->vdisplay <= m->vdisplay)
                        ok = true;
        }
        return ok;
}

static int
drm_dmt_modes_for_range(struct drm_connector *connector, struct edid *edid,
                        struct detailed_timing *timing)
{
        int i, modes = 0;
        struct drm_display_mode *newmode;
        struct drm_device *dev = connector->dev;

        for (i = 0; i < drm_num_dmt_modes; i++) {
                if (mode_in_range(drm_dmt_modes + i, edid, timing) &&
                    valid_inferred_mode(connector, drm_dmt_modes + i)) {
                        newmode = drm_mode_duplicate(dev, &drm_dmt_modes[i]);
                        if (newmode) {
                                drm_mode_probed_add(connector, newmode);
                                modes++;
                        }
                }
        }

        return modes;
}

/* fix up 1366x768 mode from 1368x768;
 * GFT/CVT can't express 1366 width which isn't dividable by 8
 */
static void fixup_mode_1366x768(struct drm_display_mode *mode)
{
        if (mode->hdisplay == 1368 && mode->vdisplay == 768) {
                mode->hdisplay = 1366;
                mode->hsync_start--;
                mode->hsync_end--;
                drm_mode_set_name(mode);
        }
}

static int
drm_gtf_modes_for_range(struct drm_connector *connector, struct edid *edid,
                        struct detailed_timing *timing)
{
        int i, modes = 0;
        struct drm_display_mode *newmode;
        struct drm_device *dev = connector->dev;

        for (i = 0; i < num_extra_modes; i++) {
                const struct minimode *m = &extra_modes[i];
                newmode = drm_gtf_mode(dev, m->w, m->h, m->r, 0, 0);
                if (!newmode)
                        return modes;

                fixup_mode_1366x768(newmode);
                if (!mode_in_range(newmode, edid, timing) ||
                    !valid_inferred_mode(connector, newmode)) {
                        drm_mode_destroy(dev, newmode);
                        continue;
                }

                drm_mode_probed_add(connector, newmode);
                modes++;
        }

        return modes;
}

static int
drm_cvt_modes_for_range(struct drm_connector *connector, struct edid *edid,
                        struct detailed_timing *timing)
{
        int i, modes = 0;
        struct drm_display_mode *newmode;
        struct drm_device *dev = connector->dev;
        bool rb = drm_monitor_supports_rb(edid);

        for (i = 0; i < num_extra_modes; i++) {
                const struct minimode *m = &extra_modes[i];
                newmode = drm_cvt_mode(dev, m->w, m->h, m->r, rb, 0, 0);
                if (!newmode)
                        return modes;

                fixup_mode_1366x768(newmode);
                if (!mode_in_range(newmode, edid, timing) ||
                    !valid_inferred_mode(connector, newmode)) {
                        drm_mode_destroy(dev, newmode);
                        continue;
                }

                drm_mode_probed_add(connector, newmode);
                modes++;
        }

        return modes;
}

static void
do_inferred_modes(struct detailed_timing *timing, void *c)
{
        struct detailed_mode_closure *closure = c;
        struct detailed_non_pixel *data = &timing->data.other_data;
        struct detailed_data_monitor_range *range = &data->data.range;

        if (data->type != EDID_DETAIL_MONITOR_RANGE)
                return;

        closure->modes += drm_dmt_modes_for_range(closure->connector,
                                                  closure->edid,
                                                  timing);
        
        if (!version_greater(closure->edid, 1, 1))
                return; /* GTF not defined yet */

        switch (range->flags) {
        case 0x02: /* secondary gtf, XXX could do more */
        case 0x00: /* default gtf */
                closure->modes += drm_gtf_modes_for_range(closure->connector,
                                                          closure->edid,
                                                          timing);
                break;
        case 0x04: /* cvt, only in 1.4+ */
                if (!version_greater(closure->edid, 1, 3))
                        break;

                closure->modes += drm_cvt_modes_for_range(closure->connector,
                                                          closure->edid,
                                                          timing);
                break;
        case 0x01: /* just the ranges, no formula */
        default:
                break;
        }
}

static int
add_inferred_modes(struct drm_connector *connector, struct edid *edid)
{
        struct detailed_mode_closure closure = {
                connector, edid, 0, 0, 0
        };

        if (version_greater(edid, 1, 0))
                drm_for_each_detailed_block((u8 *)edid, do_inferred_modes,
                                            &closure);

        return closure.modes;
}

static int
drm_est3_modes(struct drm_connector *connector, struct detailed_timing *timing)
{
        int i, j, m, modes = 0;
        struct drm_display_mode *mode;
        u8 *est = ((u8 *)timing) + 5;

        for (i = 0; i < 6; i++) {
                for (j = 7; j > 0; j--) {
                        m = (i * 8) + (7 - j);
                        if (m >= ARRAY_SIZE(est3_modes))
                                break;
                        if (est[i] & (1 << j)) {
                                mode = drm_mode_find_dmt(connector->dev,
                                                         est3_modes[m].w,
                                                         est3_modes[m].h,
                                                         est3_modes[m].r,
                                                         est3_modes[m].rb);
                                if (mode) {
                                        drm_mode_probed_add(connector, mode);
                                        modes++;
                                }
                        }
                }
        }

        return modes;
}

static void
do_established_modes(struct detailed_timing *timing, void *c)
{
        struct detailed_mode_closure *closure = c;
        struct detailed_non_pixel *data = &timing->data.other_data;

        if (data->type == EDID_DETAIL_EST_TIMINGS)
                closure->modes += drm_est3_modes(closure->connector, timing);
}

/**
 * add_established_modes - get est. modes from EDID and add them
 * @edid: EDID block to scan
 *
 * Each EDID block contains a bitmap of the supported "established modes" list
 * (defined above).  Tease them out and add them to the global modes list.
 */
static int
add_established_modes(struct drm_connector *connector, struct edid *edid)
{
        struct drm_device *dev = connector->dev;
        unsigned long est_bits = edid->established_timings.t1 |
                (edid->established_timings.t2 << 8) |
                ((edid->established_timings.mfg_rsvd & 0x80) << 9);
        int i, modes = 0;
        struct detailed_mode_closure closure = {
                connector, edid, 0, 0, 0
        };

        for (i = 0; i <= EDID_EST_TIMINGS; i++) {
                if (est_bits & (1<<i)) {
                        struct drm_display_mode *newmode;
                        newmode = drm_mode_duplicate(dev, &edid_est_modes[i]);
                        if (newmode) {
                                drm_mode_probed_add(connector, newmode);
                                modes++;
                        }
                }
        }

        if (version_greater(edid, 1, 0))
                    drm_for_each_detailed_block((u8 *)edid,
                                                do_established_modes, &closure);

        return modes + closure.modes;
}

static void
do_standard_modes(struct detailed_timing *timing, void *c)
{
        struct detailed_mode_closure *closure = c;
        struct detailed_non_pixel *data = &timing->data.other_data;
        struct drm_connector *connector = closure->connector;
        struct edid *edid = closure->edid;

        if (data->type == EDID_DETAIL_STD_MODES) {
                int i;
                for (i = 0; i < 6; i++) {
                        struct std_timing *std;
                        struct drm_display_mode *newmode;

                        std = &data->data.timings[i];
                        newmode = drm_mode_std(connector, edid, std,
                                               edid->revision);
                        if (newmode) {
                                drm_mode_probed_add(connector, newmode);
                                closure->modes++;
                        }
                }
        }
}

/**
 * add_standard_modes - get std. modes from EDID and add them
 * @edid: EDID block to scan
 *
 * Standard modes can be calculated using the appropriate standard (DMT,
 * GTF or CVT. Grab them from @edid and add them to the list.
 */
static int
add_standard_modes(struct drm_connector *connector, struct edid *edid)
{
        int i, modes = 0;
        struct detailed_mode_closure closure = {
                connector, edid, 0, 0, 0
        };

        for (i = 0; i < EDID_STD_TIMINGS; i++) {
                struct drm_display_mode *newmode;

                newmode = drm_mode_std(connector, edid,
                                       &edid->standard_timings[i],
                                       edid->revision);
                if (newmode) {
                        drm_mode_probed_add(connector, newmode);
                        modes++;
                }
        }

        if (version_greater(edid, 1, 0))
                drm_for_each_detailed_block((u8 *)edid, do_standard_modes,
                                            &closure);

        /* XXX should also look for standard codes in VTB blocks */

        return modes + closure.modes;
}

static int drm_cvt_modes(struct drm_connector *connector,
                         struct detailed_timing *timing)
{
        int i, j, modes = 0;
        struct drm_display_mode *newmode;
        struct drm_device *dev = connector->dev;
        struct cvt_timing *cvt;
        const int rates[] = { 60, 85, 75, 60, 50 };
        const u8 empty[3] = { 0, 0, 0 };

        for (i = 0; i < 4; i++) {
                int width = 0, height;
                cvt = &(timing->data.other_data.data.cvt[i]);

                if (!memcmp(cvt->code, empty, 3))
                        continue;

                height = (cvt->code[0] + ((cvt->code[1] & 0xf0) << 4) + 1) * 2;
                switch (cvt->code[1] & 0x0c) {
                case 0x00:
                        width = height * 4 / 3;
                        break;
                case 0x04:
                        width = height * 16 / 9;
                        break;
                case 0x08:
                        width = height * 16 / 10;
                        break;
                case 0x0c:
                        width = height * 15 / 9;
                        break;
                }

                for (j = 1; j < 5; j++) {
                        if (cvt->code[2] & (1 << j)) {
                                newmode = drm_cvt_mode(dev, width, height,
                                                       rates[j], j == 0,
                                                       false, false);
                                if (newmode) {
                                        drm_mode_probed_add(connector, newmode);
                                        modes++;
                                }
                        }
                }
        }

        return modes;
}

static void
do_cvt_mode(struct detailed_timing *timing, void *c)
{
        struct detailed_mode_closure *closure = c;
        struct detailed_non_pixel *data = &timing->data.other_data;

        if (data->type == EDID_DETAIL_CVT_3BYTE)
                closure->modes += drm_cvt_modes(closure->connector, timing);
}

static int
add_cvt_modes(struct drm_connector *connector, struct edid *edid)
{       
        struct detailed_mode_closure closure = {
                connector, edid, 0, 0, 0
        };

        if (version_greater(edid, 1, 2))
                drm_for_each_detailed_block((u8 *)edid, do_cvt_mode, &closure);

        /* XXX should also look for CVT codes in VTB blocks */

        return closure.modes;
}

static void
do_detailed_mode(struct detailed_timing *timing, void *c)
{
        struct detailed_mode_closure *closure = c;
        struct drm_display_mode *newmode;

        if (timing->pixel_clock) {
                newmode = drm_mode_detailed(closure->connector->dev,
                                            closure->edid, timing,
                                            closure->quirks);
                if (!newmode)
                        return;

                if (closure->preferred)
                        newmode->type |= DRM_MODE_TYPE_PREFERRED;

                drm_mode_probed_add(closure->connector, newmode);
                closure->modes++;
                closure->preferred = 0;
        }
}

/*
 * add_detailed_modes - Add modes from detailed timings
 * @connector: attached connector
 * @edid: EDID block to scan
 * @quirks: quirks to apply
 */
static int
add_detailed_modes(struct drm_connector *connector, struct edid *edid,
                   u32 quirks)
{
        struct detailed_mode_closure closure = {
                connector,
                edid,
                1,
                quirks,
                0
        };

        if (closure.preferred && !version_greater(edid, 1, 3))
                closure.preferred =
                    (edid->features & DRM_EDID_FEATURE_PREFERRED_TIMING);

        drm_for_each_detailed_block((u8 *)edid, do_detailed_mode, &closure);

        return closure.modes;
}

#define HDMI_IDENTIFIER 0x000C03
#define AUDIO_BLOCK     0x01
#define VIDEO_BLOCK     0x02
#define VENDOR_BLOCK    0x03
#define SPEAKER_BLOCK   0x04
#define EDID_BASIC_AUDIO        (1 << 6)
#define EDID_CEA_YCRCB444       (1 << 5)
#define EDID_CEA_YCRCB422       (1 << 4)

/**
 * Search EDID for CEA extension block.
 */
u8 *drm_find_cea_extension(struct edid *edid)
{
        u8 *edid_ext = NULL;
        int i;

        /* No EDID or EDID extensions */
        if (edid == NULL || edid->extensions == 0)
                return NULL;

        /* Find CEA extension */
        for (i = 0; i < edid->extensions; i++) {
                edid_ext = (u8 *)edid + EDID_LENGTH * (i + 1);
                if (edid_ext[0] == CEA_EXT)
                        break;
        }

        if (i == edid->extensions)
                return NULL;

        return edid_ext;
}
EXPORT_SYMBOL(drm_find_cea_extension);

/*
 * Looks for a CEA mode matching given drm_display_mode.
 * Returns its CEA Video ID code, or 0 if not found.
 */
u8 drm_match_cea_mode(struct drm_display_mode *to_match)
{
        const struct drm_display_mode *cea_mode;
        u8 mode;

        for (mode = 0; mode < drm_num_cea_modes; mode++) {
                cea_mode = (const struct drm_display_mode *)&edid_cea_modes[mode];

                if (drm_mode_equal(to_match, cea_mode))
                        return mode + 1;
        }
        return 0;
}
EXPORT_SYMBOL(drm_match_cea_mode);


static int
do_cea_modes (struct drm_connector *connector, u8 *db, u8 len)
{
        struct drm_device *dev = connector->dev;
        u8 * mode, cea_mode;
        int modes = 0;

        for (mode = db; mode < db + len; mode++) {
                cea_mode = (*mode & 127) - 1; /* CEA modes are numbered 1..127 */
                if (cea_mode < drm_num_cea_modes) {
                        struct drm_display_mode *newmode;
                        newmode = drm_mode_duplicate(dev,
                                                     &edid_cea_modes[cea_mode]);
                        if (newmode) {
                                drm_mode_probed_add(connector, newmode);
                                modes++;
                        }
                }
        }

        return modes;
}

static int
cea_db_payload_len(const u8 *db)
{
        return db[0] & 0x1f;
}

static int
cea_db_tag(const u8 *db)
{
        return db[0] >> 5;
}

static int
cea_revision(const u8 *cea)
{
        return cea[1];
}

static int
cea_db_offsets(const u8 *cea, int *start, int *end)
{
        /* Data block offset in CEA extension block */
        *start = 4;
        *end = cea[2];
        if (*end == 0)
                *end = 127;
        if (*end < 4 || *end > 127)
                return -ERANGE;
        return 0;
}

#define for_each_cea_db(cea, i, start, end) \
        for ((i) = (start); (i) < (end) && (i) + cea_db_payload_len(&(cea)[(i)]) < (end); (i) += cea_db_payload_len(&(cea)[(i)]) + 1)

static int
add_cea_modes(struct drm_connector *connector, struct edid *edid)
{
        u8 * cea = drm_find_cea_extension(edid);
        u8 * db, dbl;
        int modes = 0;

        if (cea && cea_revision(cea) >= 3) {
                int i, start, end;

                if (cea_db_offsets(cea, &start, &end))
                        return 0;

                for_each_cea_db(cea, i, start, end) {
                        db = &cea[i];
                        dbl = cea_db_payload_len(db);

                        if (cea_db_tag(db) == VIDEO_BLOCK)
                                modes += do_cea_modes (connector, db+1, dbl);
                }
        }

        return modes;
}

static void
parse_hdmi_vsdb(struct drm_connector *connector, const u8 *db)
{
        u8 len = cea_db_payload_len(db);

        if (len >= 6) {
                connector->eld[5] |= (db[6] >> 7) << 1;  /* Supports_AI */
                connector->dvi_dual = db[6] & 1;
        }
        if (len >= 7)
                connector->max_tmds_clock = db[7] * 5;
        if (len >= 8) {
                connector->latency_present[0] = db[8] >> 7;
                connector->latency_present[1] = (db[8] >> 6) & 1;
        }
        if (len >= 9)
                connector->video_latency[0] = db[9];
        if (len >= 10)
                connector->audio_latency[0] = db[10];
        if (len >= 11)
                connector->video_latency[1] = db[11];
        if (len >= 12)
                connector->audio_latency[1] = db[12];

        DRM_DEBUG_KMS("HDMI: DVI dual %d, "
                    "max TMDS clock %d, "
                    "latency present %d %d, "
                    "video latency %d %d, "
                    "audio latency %d %d\n",
                    connector->dvi_dual,
                    connector->max_tmds_clock,
              (int) connector->latency_present[0],
              (int) connector->latency_present[1],
                    connector->video_latency[0],
                    connector->video_latency[1],
                    connector->audio_latency[0],
                    connector->audio_latency[1]);
}

static void
monitor_name(struct detailed_timing *t, void *data)
{
        if (t->data.other_data.type == EDID_DETAIL_MONITOR_NAME)
                *(u8 **)data = t->data.other_data.data.str.str;
}

static bool cea_db_is_hdmi_vsdb(const u8 *db)
{
        int hdmi_id;

        if (cea_db_tag(db) != VENDOR_BLOCK)
                return false;

        if (cea_db_payload_len(db) < 5)
                return false;

        hdmi_id = db[1] | (db[2] << 8) | (db[3] << 16);

        return hdmi_id == HDMI_IDENTIFIER;
}

/**
 * drm_edid_to_eld - build ELD from EDID
 * @connector: connector corresponding to the HDMI/DP sink
 * @edid: EDID to parse
 *
 * Fill the ELD (EDID-Like Data) buffer for passing to the audio driver.
 * Some ELD fields are left to the graphics driver caller:
 * - Conn_Type
 * - HDCP
 * - Port_ID
 */
void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
{
        uint8_t *eld = connector->eld;
        u8 *cea;
        u8 *name;
        u8 *db;
        int sad_count = 0;
        int mnl;
        int dbl;

        memset(eld, 0, sizeof(connector->eld));

        cea = drm_find_cea_extension(edid);
        if (!cea) {
                DRM_DEBUG_KMS("ELD: no CEA Extension found\n");
                return;
        }

        name = NULL;
        drm_for_each_detailed_block((u8 *)edid, monitor_name, &name);
        for (mnl = 0; name && mnl < 13; mnl++) {
                if (name[mnl] == 0x0a)
                        break;
                eld[20 + mnl] = name[mnl];
        }
        eld[4] = (cea[1] << 5) | mnl;
        DRM_DEBUG_KMS("ELD monitor %s\n", eld + 20);

        eld[0] = 2 << 3;                /* ELD version: 2 */

        eld[16] = edid->mfg_id[0];
        eld[17] = edid->mfg_id[1];
        eld[18] = edid->prod_code[0];
        eld[19] = edid->prod_code[1];

        if (cea_revision(cea) >= 3) {
                int i, start, end;

                if (cea_db_offsets(cea, &start, &end)) {
                        start = 0;
                        end = 0;
                }

                for_each_cea_db(cea, i, start, end) {
                        db = &cea[i];
                        dbl = cea_db_payload_len(db);

                        switch (cea_db_tag(db)) {
                        case AUDIO_BLOCK:
                                /* Audio Data Block, contains SADs */
                                sad_count = dbl / 3;
                                if (dbl >= 1)
                                        memcpy(eld + 20 + mnl, &db[1], dbl);
                                break;
                        case SPEAKER_BLOCK:
                                /* Speaker Allocation Data Block */
                                if (dbl >= 1)
                                        eld[7] = db[1];
                                break;
                        case VENDOR_BLOCK:
                                /* HDMI Vendor-Specific Data Block */
                                if (cea_db_is_hdmi_vsdb(db))
                                        parse_hdmi_vsdb(connector, db);
                                break;
                        default:
                                break;
                        }
                }
        }
        eld[5] |= sad_count << 4;
        eld[2] = (20 + mnl + sad_count * 3 + 3) / 4;

        DRM_DEBUG_KMS("ELD size %d, SAD count %d\n", (int)eld[2], sad_count);
}
EXPORT_SYMBOL(drm_edid_to_eld);

/**
 * drm_av_sync_delay - HDMI/DP sink audio-video sync delay in millisecond
 * @connector: connector associated with the HDMI/DP sink
 * @mode: the display mode
 */
int drm_av_sync_delay(struct drm_connector *connector,
                      struct drm_display_mode *mode)
{
        int i = !!(mode->flags & DRM_MODE_FLAG_INTERLACE);
        int a, v;

        if (!connector->latency_present[0])
                return 0;
        if (!connector->latency_present[1])
                i = 0;

        a = connector->audio_latency[i];
        v = connector->video_latency[i];

        /*
         * HDMI/DP sink doesn't support audio or video?
         */
        if (a == 255 || v == 255)
                return 0;

        /*
         * Convert raw EDID values to millisecond.
         * Treat unknown latency as 0ms.
         */
        if (a)
                a = min(2 * (a - 1), 500);
        if (v)
                v = min(2 * (v - 1), 500);

        return max(v - a, 0);
}
EXPORT_SYMBOL(drm_av_sync_delay);

/**
 * drm_select_eld - select one ELD from multiple HDMI/DP sinks
 * @encoder: the encoder just changed display mode
 * @mode: the adjusted display mode
 *
 * It's possible for one encoder to be associated with multiple HDMI/DP sinks.
 * The policy is now hard coded to simply use the first HDMI/DP sink's ELD.
 */
struct drm_connector *drm_select_eld(struct drm_encoder *encoder,
                                     struct drm_display_mode *mode)
{
        struct drm_connector *connector;
        struct drm_device *dev = encoder->dev;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head)
                if (connector->encoder == encoder && connector->eld[0])
                        return connector;

        return NULL;
}
EXPORT_SYMBOL(drm_select_eld);

/**
 * drm_detect_hdmi_monitor - detect whether monitor is hdmi.
 * @edid: monitor EDID information
 *
 * Parse the CEA extension according to CEA-861-B.
 * Return true if HDMI, false if not or unknown.
 */
bool drm_detect_hdmi_monitor(struct edid *edid)
{
        u8 *edid_ext;
        int i;
        int start_offset, end_offset;

        edid_ext = drm_find_cea_extension(edid);
        if (!edid_ext)
                return false;

        if (cea_db_offsets(edid_ext, &start_offset, &end_offset))
                return false;

        /*
         * Because HDMI identifier is in Vendor Specific Block,
         * search it from all data blocks of CEA extension.
         */
        for_each_cea_db(edid_ext, i, start_offset, end_offset) {
                if (cea_db_is_hdmi_vsdb(&edid_ext[i]))
                        return true;
        }

        return false;
}
EXPORT_SYMBOL(drm_detect_hdmi_monitor);

/**
 * drm_detect_monitor_audio - check monitor audio capability
 *
 * Monitor should have CEA extension block.
 * If monitor has 'basic audio', but no CEA audio blocks, it's 'basic
 * audio' only. If there is any audio extension block and supported
 * audio format, assume at least 'basic audio' support, even if 'basic
 * audio' is not defined in EDID.
 *
 */
bool drm_detect_monitor_audio(struct edid *edid)
{
        u8 *edid_ext;
        int i, j;
        bool has_audio = false;
        int start_offset, end_offset;

        edid_ext = drm_find_cea_extension(edid);
        if (!edid_ext)
                goto end;

        has_audio = ((edid_ext[3] & EDID_BASIC_AUDIO) != 0);

        if (has_audio) {
                DRM_DEBUG_KMS("Monitor has basic audio support\n");
                goto end;
        }

        if (cea_db_offsets(edid_ext, &start_offset, &end_offset))
                goto end;

        for_each_cea_db(edid_ext, i, start_offset, end_offset) {
                if (cea_db_tag(&edid_ext[i]) == AUDIO_BLOCK) {
                        has_audio = true;
                        for (j = 1; j < cea_db_payload_len(&edid_ext[i]) + 1; j += 3)
                                DRM_DEBUG_KMS("CEA audio format %d\n",
                                              (edid_ext[i + j] >> 3) & 0xf);
                        goto end;
                }
        }
end:
        return has_audio;
}
EXPORT_SYMBOL(drm_detect_monitor_audio);

/**
 * drm_add_display_info - pull display info out if present
 * @edid: EDID data
 * @info: display info (attached to connector)
 *
 * Grab any available display info and stuff it into the drm_display_info
 * structure that's part of the connector.  Useful for tracking bpp and
 * color spaces.
 */
static void drm_add_display_info(struct edid *edid,
                                 struct drm_display_info *info)
{
        u8 *edid_ext;

        info->width_mm = edid->width_cm * 10;
        info->height_mm = edid->height_cm * 10;

        /* driver figures it out in this case */
        info->bpc = 0;
        info->color_formats = 0;

        if (edid->revision < 3)
                return;

        if (!(edid->input & DRM_EDID_INPUT_DIGITAL))
                return;

        /* Get data from CEA blocks if present */
        edid_ext = drm_find_cea_extension(edid);
        if (edid_ext) {
                info->cea_rev = edid_ext[1];

                /* The existence of a CEA block should imply RGB support */
                info->color_formats = DRM_COLOR_FORMAT_RGB444;
                if (edid_ext[3] & EDID_CEA_YCRCB444)
                        info->color_formats |= DRM_COLOR_FORMAT_YCRCB444;
                if (edid_ext[3] & EDID_CEA_YCRCB422)
                        info->color_formats |= DRM_COLOR_FORMAT_YCRCB422;
        }

        /* Only defined for 1.4 with digital displays */
        if (edid->revision < 4)
                return;

        switch (edid->input & DRM_EDID_DIGITAL_DEPTH_MASK) {
        case DRM_EDID_DIGITAL_DEPTH_6:
                info->bpc = 6;
                break;
        case DRM_EDID_DIGITAL_DEPTH_8:
                info->bpc = 8;
                break;
        case DRM_EDID_DIGITAL_DEPTH_10:
                info->bpc = 10;
                break;
        case DRM_EDID_DIGITAL_DEPTH_12:
                info->bpc = 12;
                break;
        case DRM_EDID_DIGITAL_DEPTH_14:
                info->bpc = 14;
                break;
        case DRM_EDID_DIGITAL_DEPTH_16:
                info->bpc = 16;
                break;
        case DRM_EDID_DIGITAL_DEPTH_UNDEF:
        default:
                info->bpc = 0;
                break;
        }

        info->color_formats |= DRM_COLOR_FORMAT_RGB444;
        if (edid->features & DRM_EDID_FEATURE_RGB_YCRCB444)
                info->color_formats |= DRM_COLOR_FORMAT_YCRCB444;
        if (edid->features & DRM_EDID_FEATURE_RGB_YCRCB422)
                info->color_formats |= DRM_COLOR_FORMAT_YCRCB422;
}

/**
 * drm_add_edid_modes - add modes from EDID data, if available
 * @connector: connector we're probing
 * @edid: edid data
 *
 * Add the specified modes to the connector's mode list.
 *
 * Return number of modes added or 0 if we couldn't find any.
 */
int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
{
        int num_modes = 0;
        u32 quirks;

        if (edid == NULL) {
                return 0;
        }
        if (!drm_edid_is_valid(edid)) {
                dev_warn(connector->dev->dev, "%s: EDID invalid.\n",
                         drm_get_connector_name(connector));
                return 0;
        }

        quirks = edid_get_quirks(edid);

        /*
         * EDID spec says modes should be preferred in this order:
         * - preferred detailed mode
         * - other detailed modes from base block
         * - detailed modes from extension blocks
         * - CVT 3-byte code modes
         * - standard timing codes
         * - established timing codes
         * - modes inferred from GTF or CVT range information
         *
         * We get this pretty much right.
         *
         * XXX order for additional mode types in extension blocks?
         */
        num_modes += add_detailed_modes(connector, edid, quirks);
        num_modes += add_cvt_modes(connector, edid);
        num_modes += add_standard_modes(connector, edid);
        num_modes += add_established_modes(connector, edid);
        if (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF)
                num_modes += add_inferred_modes(connector, edid);
        num_modes += add_cea_modes(connector, edid);

        if (quirks & (EDID_QUIRK_PREFER_LARGE_60 | EDID_QUIRK_PREFER_LARGE_75))
                edid_fixup_preferred(connector, quirks);

        drm_add_display_info(edid, &connector->display_info);

        return num_modes;
}
EXPORT_SYMBOL(drm_add_edid_modes);

/**
 * drm_add_modes_noedid - add modes for the connectors without EDID
 * @connector: connector we're probing
 * @hdisplay: the horizontal display limit
 * @vdisplay: the vertical display limit
 *
 * Add the specified modes to the connector's mode list. Only when the
 * hdisplay/vdisplay is not beyond the given limit, it will be added.
 *
 * Return number of modes added or 0 if we couldn't find any.
 */
int drm_add_modes_noedid(struct drm_connector *connector,
                        int hdisplay, int vdisplay)
{
        int i, count, num_modes = 0;
        struct drm_display_mode *mode;
        struct drm_device *dev = connector->dev;

        count = sizeof(drm_dmt_modes) / sizeof(struct drm_display_mode);
        if (hdisplay < 0)
                hdisplay = 0;
        if (vdisplay < 0)
                vdisplay = 0;

        for (i = 0; i < count; i++) {
                const struct drm_display_mode *ptr = &drm_dmt_modes[i];
                if (hdisplay && vdisplay) {
                        /*
                         * Only when two are valid, they will be used to check
                         * whether the mode should be added to the mode list of
                         * the connector.
                         */
                        if (ptr->hdisplay > hdisplay ||
                                        ptr->vdisplay > vdisplay)
                                continue;
                }
                if (drm_mode_vrefresh(ptr) > 61)
                        continue;
                mode = drm_mode_duplicate(dev, ptr);
                if (mode) {
                        drm_mode_probed_add(connector, mode);
                        num_modes++;
                }
        }
        return num_modes;
}
EXPORT_SYMBOL(drm_add_modes_noedid);

/**
 * drm_mode_cea_vic - return the CEA-861 VIC of a given mode
 * @mode: mode
 *
 * RETURNS:
 * The VIC number, 0 in case it's not a CEA-861 mode.
 */
uint8_t drm_mode_cea_vic(const struct drm_display_mode *mode)
{
        uint8_t i;

        for (i = 0; i < drm_num_cea_modes; i++)
                if (drm_mode_equal(mode, &edid_cea_modes[i]))
                        return i + 1;

        return 0;
}
EXPORT_SYMBOL(drm_mode_cea_vic);