/*
 * Copyright (c) 2006-2008 Intel Corporation
 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
 *
 * DRM core CRTC related functions
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 *
 * Authors:
 *      Keith Packard
 *      Eric Anholt <eric@anholt.net>
 *      Dave Airlie <airlied@linux.ie>
 *      Jesse Barnes <jesse.barnes@intel.com>
 */

#include <linux/export.h>
#include <linux/moduleparam.h>

#include <drm/drm_bridge.h>
#include <drm/drm_client_event.h>
#include <drm/drm_crtc.h>
#include <drm/drm_edid.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_managed.h>
#include <drm/drm_modeset_helper_vtables.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_sysfs.h>

#include "drm_crtc_helper_internal.h"

/**
 * DOC: output probing helper overview
 *
 * This library provides some helper code for output probing. It provides an
 * implementation of the core &drm_connector_funcs.fill_modes interface with
 * drm_helper_probe_single_connector_modes().
 *
 * It also provides support for polling connectors with a work item and for
 * generic hotplug interrupt handling where the driver doesn't or cannot keep
 * track of a per-connector hpd interrupt.
 *
 * This helper library can be used independently of the modeset helper library.
 * Drivers can also overwrite different parts e.g. use their own hotplug
 * handling code to avoid probing unrelated outputs.
 *
 * The probe helpers share the function table structures with other display
 * helper libraries. See &struct drm_connector_helper_funcs for the details.
 */

static bool drm_kms_helper_poll = true;
module_param_named(poll, drm_kms_helper_poll, bool, 0600);

static enum drm_mode_status
drm_mode_validate_flag(const struct drm_display_mode *mode,
                       int flags)
{
        if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
            !(flags & DRM_MODE_FLAG_INTERLACE))
                return MODE_NO_INTERLACE;

        if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
            !(flags & DRM_MODE_FLAG_DBLSCAN))
                return MODE_NO_DBLESCAN;

        if ((mode->flags & DRM_MODE_FLAG_3D_MASK) &&
            !(flags & DRM_MODE_FLAG_3D_MASK))
                return MODE_NO_STEREO;

        return MODE_OK;
}

static int
drm_mode_validate_pipeline(struct drm_display_mode *mode,
                           struct drm_connector *connector,
                           struct drm_modeset_acquire_ctx *ctx,
                           enum drm_mode_status *status)
{
        struct drm_device *dev = connector->dev;
        struct drm_encoder *encoder;
        int ret;

        /* Step 1: Validate against connector */
        ret = drm_connector_mode_valid(connector, mode, ctx, status);
        if (ret || *status != MODE_OK)
                return ret;

        /* Step 2: Validate against encoders and crtcs */
        drm_connector_for_each_possible_encoder(connector, encoder) {
                struct drm_bridge *bridge;
                struct drm_crtc *crtc;

                *status = drm_encoder_mode_valid(encoder, mode);
                if (*status != MODE_OK) {
                        /* No point in continuing for crtc check as this encoder
                         * will not accept the mode anyway. If all encoders
                         * reject the mode then, at exit, ret will not be
                         * MODE_OK. */
                        continue;
                }

                bridge = drm_bridge_chain_get_first_bridge(encoder);
                *status = drm_bridge_chain_mode_valid(bridge,
                                                      &connector->display_info,
                                                      mode);
                drm_bridge_put(bridge);
                if (*status != MODE_OK) {
                        /* There is also no point in continuing for crtc check
                         * here. */
                        continue;
                }

                drm_for_each_crtc(crtc, dev) {
                        if (!drm_encoder_crtc_ok(encoder, crtc))
                                continue;

                        *status = drm_crtc_mode_valid(crtc, mode);
                        if (*status == MODE_OK) {
                                /* If we get to this point there is at least
                                 * one combination of encoder+crtc that works
                                 * for this mode. Lets return now. */
                                return 0;
                        }
                }
        }

        return 0;
}

static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
{
        struct drm_cmdline_mode *cmdline_mode;
        struct drm_display_mode *mode;

        cmdline_mode = &connector->cmdline_mode;
        if (!cmdline_mode->specified)
                return 0;

        /* Only add a GTF mode if we find no matching probed modes */
        list_for_each_entry(mode, &connector->probed_modes, head) {
                if (mode->hdisplay != cmdline_mode->xres ||
                    mode->vdisplay != cmdline_mode->yres)
                        continue;

                if (cmdline_mode->refresh_specified) {
                        /* The probed mode's vrefresh is set until later */
                        if (drm_mode_vrefresh(mode) != cmdline_mode->refresh)
                                continue;
                }

                /* Mark the matching mode as being preferred by the user */
                mode->type |= DRM_MODE_TYPE_USERDEF;
                return 0;
        }

        mode = drm_mode_create_from_cmdline_mode(connector->dev,
                                                 cmdline_mode);
        if (mode == NULL)
                return 0;

        drm_mode_probed_add(connector, mode);
        return 1;
}

enum drm_mode_status drm_crtc_mode_valid(struct drm_crtc *crtc,
                                         const struct drm_display_mode *mode)
{
        const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;

        if (!crtc_funcs || !crtc_funcs->mode_valid)
                return MODE_OK;

        return crtc_funcs->mode_valid(crtc, mode);
}

enum drm_mode_status drm_encoder_mode_valid(struct drm_encoder *encoder,
                                            const struct drm_display_mode *mode)
{
        const struct drm_encoder_helper_funcs *encoder_funcs =
                encoder->helper_private;

        if (!encoder_funcs || !encoder_funcs->mode_valid)
                return MODE_OK;

        return encoder_funcs->mode_valid(encoder, mode);
}

int
drm_connector_mode_valid(struct drm_connector *connector,
                         const struct drm_display_mode *mode,
                         struct drm_modeset_acquire_ctx *ctx,
                         enum drm_mode_status *status)
{
        const struct drm_connector_helper_funcs *connector_funcs =
                connector->helper_private;
        int ret = 0;

        if (!connector_funcs)
                *status = MODE_OK;
        else if (connector_funcs->mode_valid_ctx)
                ret = connector_funcs->mode_valid_ctx(connector, mode, ctx,
                                                      status);
        else if (connector_funcs->mode_valid)
                *status = connector_funcs->mode_valid(connector, mode);
        else
                *status = MODE_OK;

        return ret;
}

static void drm_kms_helper_disable_hpd(struct drm_device *dev)
{
        struct drm_connector *connector;
        struct drm_connector_list_iter conn_iter;

        drm_connector_list_iter_begin(dev, &conn_iter);
        drm_for_each_connector_iter(connector, &conn_iter) {
                const struct drm_connector_helper_funcs *funcs =
                        connector->helper_private;

                if (funcs && funcs->disable_hpd)
                        funcs->disable_hpd(connector);
        }
        drm_connector_list_iter_end(&conn_iter);
}

static bool drm_kms_helper_enable_hpd(struct drm_device *dev)
{
        bool poll = false;
        struct drm_connector *connector;
        struct drm_connector_list_iter conn_iter;

        drm_connector_list_iter_begin(dev, &conn_iter);
        drm_for_each_connector_iter(connector, &conn_iter) {
                const struct drm_connector_helper_funcs *funcs =
                        connector->helper_private;

                if (funcs && funcs->enable_hpd)
                        funcs->enable_hpd(connector);

                if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
                                         DRM_CONNECTOR_POLL_DISCONNECT))
                        poll = true;
        }
        drm_connector_list_iter_end(&conn_iter);

        return poll;
}

#define DRM_OUTPUT_POLL_PERIOD (10*HZ)
static void reschedule_output_poll_work(struct drm_device *dev)
{
        unsigned long delay = DRM_OUTPUT_POLL_PERIOD;

        if (dev->mode_config.delayed_event)
                /*
                 * FIXME:
                 *
                 * Use short (1s) delay to handle the initial delayed event.
                 * This delay should not be needed, but Optimus/nouveau will
                 * fail in a mysterious way if the delayed event is handled as
                 * soon as possible like it is done in
                 * drm_helper_probe_single_connector_modes() in case the poll
                 * was enabled before.
                 */
                delay = HZ;

        schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
}

/**
 * drm_kms_helper_poll_enable - re-enable output polling.
 * @dev: drm_device
 *
 * This function re-enables the output polling work, after it has been
 * temporarily disabled using drm_kms_helper_poll_disable(), for example over
 * suspend/resume.
 *
 * Drivers can call this helper from their device resume implementation. It is
 * not an error to call this even when output polling isn't enabled.
 *
 * If device polling was never initialized before, this call will trigger a
 * warning and return.
 *
 * Note that calls to enable and disable polling must be strictly ordered, which
 * is automatically the case when they're only call from suspend/resume
 * callbacks.
 */
void drm_kms_helper_poll_enable(struct drm_device *dev)
{
        if (drm_WARN_ON_ONCE(dev, !dev->mode_config.poll_enabled) ||
            !drm_kms_helper_poll || dev->mode_config.poll_running)
                return;

        if (drm_kms_helper_enable_hpd(dev) ||
            dev->mode_config.delayed_event)
                reschedule_output_poll_work(dev);

        dev->mode_config.poll_running = true;
}
EXPORT_SYMBOL(drm_kms_helper_poll_enable);

/**
 * drm_kms_helper_poll_reschedule - reschedule the output polling work
 * @dev: drm_device
 *
 * This function reschedules the output polling work, after polling for a
 * connector has been enabled.
 *
 * Drivers must call this helper after enabling polling for a connector by
 * setting %DRM_CONNECTOR_POLL_CONNECT / %DRM_CONNECTOR_POLL_DISCONNECT flags
 * in drm_connector::polled. Note that after disabling polling by clearing these
 * flags for a connector will stop the output polling work automatically if
 * the polling is disabled for all other connectors as well.
 *
 * The function can be called only after polling has been enabled by calling
 * drm_kms_helper_poll_init() / drm_kms_helper_poll_enable().
 */
void drm_kms_helper_poll_reschedule(struct drm_device *dev)
{
        if (dev->mode_config.poll_running)
                reschedule_output_poll_work(dev);
}
EXPORT_SYMBOL(drm_kms_helper_poll_reschedule);

static int detect_connector_status(struct drm_connector *connector,
                                   struct drm_modeset_acquire_ctx *ctx,
                                   bool force)
{
        const struct drm_connector_helper_funcs *funcs = connector->helper_private;

        if (funcs->detect_ctx)
                return funcs->detect_ctx(connector, ctx, force);
        else if (connector->funcs->detect)
                return connector->funcs->detect(connector, force);

        return connector_status_connected;
}

static enum drm_connector_status
drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
{
        struct drm_modeset_acquire_ctx ctx;
        int ret;

        drm_modeset_acquire_init(&ctx, 0);

retry:
        ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex, &ctx);
        if (!ret)
                ret = detect_connector_status(connector, &ctx, force);

        if (ret == -EDEADLK) {
                drm_modeset_backoff(&ctx);
                goto retry;
        }

        if (WARN_ON(ret < 0))
                ret = connector_status_unknown;

        if (ret != connector->status)
                connector->epoch_counter += 1;

        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);

        return ret;
}

/**
 * drm_helper_probe_detect - probe connector status
 * @connector: connector to probe
 * @ctx: acquire_ctx, or NULL to let this function handle locking.
 * @force: Whether destructive probe operations should be performed.
 *
 * This function calls the detect callbacks of the connector.
 * This function returns &drm_connector_status, or
 * if @ctx is set, it might also return -EDEADLK.
 */
int
drm_helper_probe_detect(struct drm_connector *connector,
                        struct drm_modeset_acquire_ctx *ctx,
                        bool force)
{
        struct drm_device *dev = connector->dev;
        int ret;

        if (!ctx)
                return drm_helper_probe_detect_ctx(connector, force);

        ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
        if (ret)
                return ret;

        ret = detect_connector_status(connector, ctx, force);

        if (ret != connector->status)
                connector->epoch_counter += 1;

        return ret;
}
EXPORT_SYMBOL(drm_helper_probe_detect);

static int drm_helper_probe_get_modes(struct drm_connector *connector)
{
        const struct drm_connector_helper_funcs *connector_funcs =
                connector->helper_private;
        int count;

        count = connector_funcs->get_modes(connector);

        /* The .get_modes() callback should not return negative values. */
        if (count < 0) {
                drm_err(connector->dev, ".get_modes() returned %pe\n",
                        ERR_PTR(count));
                count = 0;
        }

        /*
         * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
         * override/firmware EDID.
         */
        if (count == 0 && connector->status == connector_status_connected)
                count = drm_edid_override_connector_update(connector);

        return count;
}

static int __drm_helper_update_and_validate(struct drm_connector *connector,
                                            uint32_t maxX, uint32_t maxY,
                                            struct drm_modeset_acquire_ctx *ctx)
{
        struct drm_device *dev = connector->dev;
        struct drm_display_mode *mode;
        int mode_flags = 0;
        int ret;

        drm_connector_list_update(connector);

        if (connector->interlace_allowed)
                mode_flags |= DRM_MODE_FLAG_INTERLACE;
        if (connector->doublescan_allowed)
                mode_flags |= DRM_MODE_FLAG_DBLSCAN;
        if (connector->stereo_allowed)
                mode_flags |= DRM_MODE_FLAG_3D_MASK;

        list_for_each_entry(mode, &connector->modes, head) {
                if (mode->status != MODE_OK)
                        continue;

                mode->status = drm_mode_validate_driver(dev, mode);
                if (mode->status != MODE_OK)
                        continue;

                mode->status = drm_mode_validate_size(mode, maxX, maxY);
                if (mode->status != MODE_OK)
                        continue;

                mode->status = drm_mode_validate_flag(mode, mode_flags);
                if (mode->status != MODE_OK)
                        continue;

                mode->status = drm_mode_validate_ycbcr420(mode, connector);
                if (mode->status != MODE_OK)
                        continue;

                ret = drm_mode_validate_pipeline(mode, connector, ctx,
                                                 &mode->status);
                if (ret) {
                        drm_dbg_kms(dev,
                                    "drm_mode_validate_pipeline failed: %d\n",
                                    ret);

                        if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
                                mode->status = MODE_ERROR;
                        else
                                return -EDEADLK;
                }
        }

        return 0;
}

/**
 * drm_helper_probe_single_connector_modes - get complete set of display modes
 * @connector: connector to probe
 * @maxX: max width for modes
 * @maxY: max height for modes
 *
 * Based on the helper callbacks implemented by @connector in struct
 * &drm_connector_helper_funcs try to detect all valid modes.  Modes will first
 * be added to the connector's probed_modes list, then culled (based on validity
 * and the @maxX, @maxY parameters) and put into the normal modes list.
 *
 * Intended to be used as a generic implementation of the
 * &drm_connector_funcs.fill_modes() vfunc for drivers that use the CRTC helpers
 * for output mode filtering and detection.
 *
 * The basic procedure is as follows
 *
 * 1. All modes currently on the connector's modes list are marked as stale
 *
 * 2. New modes are added to the connector's probed_modes list with
 *    drm_mode_probed_add(). New modes start their life with status as OK.
 *    Modes are added from a single source using the following priority order.
 *
 *    - &drm_connector_helper_funcs.get_modes vfunc
 *    - if the connector status is connector_status_connected, standard
 *      VESA DMT modes up to 1024x768 are automatically added
 *      (drm_add_modes_noedid())
 *
 *    Finally modes specified via the kernel command line (video=...) are
 *    added in addition to what the earlier probes produced
 *    (drm_helper_probe_add_cmdline_mode()). These modes are generated
 *    using the VESA GTF/CVT formulas.
 *
 * 3. Modes are moved from the probed_modes list to the modes list. Potential
 *    duplicates are merged together (see drm_connector_list_update()).
 *    After this step the probed_modes list will be empty again.
 *
 * 4. Any non-stale mode on the modes list then undergoes validation
 *
 *    - drm_mode_validate_basic() performs basic sanity checks
 *    - drm_mode_validate_size() filters out modes larger than @maxX and @maxY
 *      (if specified)
 *    - drm_mode_validate_flag() checks the modes against basic connector
 *      capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
 *    - the optional &drm_connector_helper_funcs.mode_valid or
 *      &drm_connector_helper_funcs.mode_valid_ctx helpers can perform driver
 *      and/or sink specific checks
 *    - the optional &drm_crtc_helper_funcs.mode_valid,
 *      &drm_bridge_funcs.mode_valid and &drm_encoder_helper_funcs.mode_valid
 *      helpers can perform driver and/or source specific checks which are also
 *      enforced by the modeset/atomic helpers
 *
 * 5. Any mode whose status is not OK is pruned from the connector's modes list,
 *    accompanied by a debug message indicating the reason for the mode's
 *    rejection (see drm_mode_prune_invalid()).
 *
 * Returns:
 * The number of modes found on @connector.
 */
int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
                                            uint32_t maxX, uint32_t maxY)
{
        struct drm_device *dev = connector->dev;
        struct drm_display_mode *mode;
        int count = 0, ret;
        enum drm_connector_status old_status;
        struct drm_modeset_acquire_ctx ctx;

        WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));

        drm_modeset_acquire_init(&ctx, 0);

        drm_dbg_kms(dev, "[CONNECTOR:%d:%s]\n", connector->base.id,
                    connector->name);

retry:
        ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
        if (ret == -EDEADLK) {
                drm_modeset_backoff(&ctx);
                goto retry;
        } else
                WARN_ON(ret < 0);

        /* set all old modes to the stale state */
        list_for_each_entry(mode, &connector->modes, head)
                mode->status = MODE_STALE;

        old_status = connector->status;

        if (connector->force) {
                if (connector->force == DRM_FORCE_ON ||
                    connector->force == DRM_FORCE_ON_DIGITAL)
                        connector->status = connector_status_connected;
                else
                        connector->status = connector_status_disconnected;
                if (connector->funcs->force)
                        connector->funcs->force(connector);
        } else {
                ret = drm_helper_probe_detect(connector, &ctx, true);

                if (ret == -EDEADLK) {
                        drm_modeset_backoff(&ctx);
                        goto retry;
                } else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
                        ret = connector_status_unknown;

                connector->status = ret;
        }

        /*
         * Normally either the driver's hpd code or the poll loop should
         * pick up any changes and fire the hotplug event. But if
         * userspace sneaks in a probe, we might miss a change. Hence
         * check here, and if anything changed start the hotplug code.
         */
        if (old_status != connector->status) {
                drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s\n",
                            connector->base.id, connector->name,
                            drm_get_connector_status_name(old_status),
                            drm_get_connector_status_name(connector->status));

                /*
                 * The hotplug event code might call into the fb
                 * helpers, and so expects that we do not hold any
                 * locks. Fire up the poll struct instead, it will
                 * disable itself again.
                 */
                dev->mode_config.delayed_event = true;
                if (dev->mode_config.poll_enabled)
                        mod_delayed_work(system_wq,
                                         &dev->mode_config.output_poll_work,
                                         0);
        }

        /*
         * Re-enable polling in case the global poll config changed but polling
         * is still initialized.
         */
        if (dev->mode_config.poll_enabled)
                drm_kms_helper_poll_enable(dev);

        if (connector->status == connector_status_disconnected) {
                drm_dbg_kms(dev, "[CONNECTOR:%d:%s] disconnected\n",
                            connector->base.id, connector->name);
                drm_connector_update_edid_property(connector, NULL);
                drm_mode_prune_invalid(dev, &connector->modes, false);
                goto exit;
        }

        count = drm_helper_probe_get_modes(connector);

        if (count == 0 && (connector->status == connector_status_connected ||
                           connector->status == connector_status_unknown)) {
                count = drm_add_modes_noedid(connector, 1024, 768);

                /*
                 * Section 4.2.2.6 (EDID Corruption Detection) of the DP 1.4a
                 * Link CTS specifies that 640x480 (the official "failsafe"
                 * mode) needs to be the default if there's no EDID.
                 */
                if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort)
                        drm_set_preferred_mode(connector, 640, 480);
        }
        count += drm_helper_probe_add_cmdline_mode(connector);
        if (count != 0) {
                ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
                if (ret == -EDEADLK) {
                        drm_modeset_backoff(&ctx);
                        goto retry;
                }
        }

        drm_mode_prune_invalid(dev, &connector->modes, true);

        /*
         * Displayport spec section 5.2.1.2 ("Video Timing Format") says that
         * all detachable sinks shall support 640x480 @60Hz as a fail safe
         * mode. If all modes were pruned, perhaps because they need more
         * lanes or a higher pixel clock than available, at least try to add
         * in 640x480.
         */
        if (list_empty(&connector->modes) &&
            connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
                count = drm_add_modes_noedid(connector, 640, 480);
                ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
                if (ret == -EDEADLK) {
                        drm_modeset_backoff(&ctx);
                        goto retry;
                }
                drm_mode_prune_invalid(dev, &connector->modes, true);
        }

exit:
        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);

        if (list_empty(&connector->modes))
                return 0;

        drm_mode_sort(&connector->modes);

        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] probed modes:\n",
                    connector->base.id, connector->name);

        list_for_each_entry(mode, &connector->modes, head) {
                drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
                drm_dbg_kms(dev, "Probed mode: " DRM_MODE_FMT "\n",
                            DRM_MODE_ARG(mode));
        }

        return count;
}
EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);

/**
 * drm_kms_helper_hotplug_event - fire off KMS hotplug events
 * @dev: drm_device whose connector state changed
 *
 * This function fires off the uevent for userspace and also calls the
 * client hotplug function, which is most commonly used to inform the fbdev
 * emulation code and allow it to update the fbcon output configuration.
 *
 * Drivers should call this from their hotplug handling code when a change is
 * detected. Note that this function does not do any output detection of its
 * own, like drm_helper_hpd_irq_event() does - this is assumed to be done by the
 * driver already.
 *
 * This function must be called from process context with no mode
 * setting locks held.
 *
 * If only a single connector has changed, consider calling
 * drm_kms_helper_connector_hotplug_event() instead.
 */
void drm_kms_helper_hotplug_event(struct drm_device *dev)
{
        drm_sysfs_hotplug_event(dev);
        drm_client_dev_hotplug(dev);
}
EXPORT_SYMBOL(drm_kms_helper_hotplug_event);

/**
 * drm_kms_helper_connector_hotplug_event - fire off a KMS connector hotplug event
 * @connector: drm_connector which has changed
 *
 * This is the same as drm_kms_helper_hotplug_event(), except it fires a more
 * fine-grained uevent for a single connector.
 */
void drm_kms_helper_connector_hotplug_event(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;

        drm_sysfs_connector_hotplug_event(connector);
        drm_client_dev_hotplug(dev);
}
EXPORT_SYMBOL(drm_kms_helper_connector_hotplug_event);

static void output_poll_execute(struct work_struct *work)
{
        struct delayed_work *delayed_work = to_delayed_work(work);
        struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
        struct drm_connector *connector;
        struct drm_connector_list_iter conn_iter;
        enum drm_connector_status old_status;
        bool repoll = false, changed;
        u64 old_epoch_counter;

        if (!dev->mode_config.poll_enabled)
                return;

        /* Pick up any changes detected by the probe functions. */
        changed = dev->mode_config.delayed_event;
        dev->mode_config.delayed_event = false;

        if (!drm_kms_helper_poll) {
                if (dev->mode_config.poll_running) {
                        drm_kms_helper_disable_hpd(dev);
                        dev->mode_config.poll_running = false;
                }
                goto out;
        }

        if (!mutex_trylock(&dev->mode_config.mutex)) {
                repoll = true;
                goto out;
        }

        drm_connector_list_iter_begin(dev, &conn_iter);
        drm_for_each_connector_iter(connector, &conn_iter) {
                /* Ignore forced connectors. */
                if (connector->force)
                        continue;

                /* Ignore HPD capable connectors and connectors where we don't
                 * want any hotplug detection at all for polling. */
                if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)
                        continue;

                old_status = connector->status;
                /* if we are connected and don't want to poll for disconnect
                   skip it */
                if (old_status == connector_status_connected &&
                    !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT))
                        continue;

                repoll = true;

                old_epoch_counter = connector->epoch_counter;
                connector->status = drm_helper_probe_detect(connector, NULL, false);
                if (old_epoch_counter != connector->epoch_counter) {
                        const char *old, *new;

                        /*
                         * The poll work sets force=false when calling detect so
                         * that drivers can avoid to do disruptive tests (e.g.
                         * when load detect cycles could cause flickering on
                         * other, running displays). This bears the risk that we
                         * flip-flop between unknown here in the poll work and
                         * the real state when userspace forces a full detect
                         * call after receiving a hotplug event due to this
                         * change.
                         *
                         * Hence clamp an unknown detect status to the old
                         * value.
                         */
                        if (connector->status == connector_status_unknown) {
                                connector->status = old_status;
                                continue;
                        }

                        old = drm_get_connector_status_name(old_status);
                        new = drm_get_connector_status_name(connector->status);

                        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s\n",
                                    connector->base.id, connector->name,
                                    old, new);
                        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] epoch counter %llu -> %llu\n",
                                    connector->base.id, connector->name,
                                    old_epoch_counter, connector->epoch_counter);

                        changed = true;
                }
        }
        drm_connector_list_iter_end(&conn_iter);

        mutex_unlock(&dev->mode_config.mutex);

out:
        if (changed)
                drm_kms_helper_hotplug_event(dev);

        if (repoll)
                schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
}

/**
 * drm_kms_helper_is_poll_worker - is %current task an output poll worker?
 *
 * Determine if %current task is an output poll worker.  This can be used
 * to select distinct code paths for output polling versus other contexts.
 *
 * One use case is to avoid a deadlock between the output poll worker and
 * the autosuspend worker wherein the latter waits for polling to finish
 * upon calling drm_kms_helper_poll_disable(), while the former waits for
 * runtime suspend to finish upon calling pm_runtime_get_sync() in a
 * connector ->detect hook.
 */
bool drm_kms_helper_is_poll_worker(void)
{
        return false;
#ifdef __linux__
        struct work_struct *work = current_work();

        return work && work->func == output_poll_execute;
#endif
}
EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);

/**
 * drm_kms_helper_poll_disable - disable output polling
 * @dev: drm_device
 *
 * This function disables the output polling work.
 *
 * Drivers can call this helper from their device suspend implementation. It is
 * not an error to call this even when output polling isn't enabled or already
 * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
 *
 * If however, the polling was never initialized, this call will trigger a
 * warning and return.
 *
 * Note that calls to enable and disable polling must be strictly ordered, which
 * is automatically the case when they're only call from suspend/resume
 * callbacks.
 */
void drm_kms_helper_poll_disable(struct drm_device *dev)
{
        if (drm_WARN_ON(dev, !dev->mode_config.poll_enabled))
                return;

        if (dev->mode_config.poll_running)
                drm_kms_helper_disable_hpd(dev);

        cancel_delayed_work_sync(&dev->mode_config.output_poll_work);

        dev->mode_config.poll_running = false;
}
EXPORT_SYMBOL(drm_kms_helper_poll_disable);

/**
 * drm_kms_helper_poll_init - initialize and enable output polling
 * @dev: drm_device
 *
 * This function initializes and then also enables output polling support for
 * @dev. Drivers which do not have reliable hotplug support in hardware can use
 * this helper infrastructure to regularly poll such connectors for changes in
 * their connection state.
 *
 * Drivers can control which connectors are polled by setting the
 * DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On
 * connectors where probing live outputs can result in visual distortion drivers
 * should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this.
 * Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are
 * completely ignored by the polling logic.
 *
 * Note that a connector can be both polled and probed from the hotplug handler,
 * in case the hotplug interrupt is known to be unreliable.
 */
void drm_kms_helper_poll_init(struct drm_device *dev)
{
        INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
        dev->mode_config.poll_enabled = true;

        drm_kms_helper_poll_enable(dev);
}
EXPORT_SYMBOL(drm_kms_helper_poll_init);

/**
 * drm_kms_helper_poll_fini - disable output polling and clean it up
 * @dev: drm_device
 */
void drm_kms_helper_poll_fini(struct drm_device *dev)
{
        if (!dev->mode_config.poll_enabled)
                return;

        drm_kms_helper_poll_disable(dev);

        dev->mode_config.poll_enabled = false;
}
EXPORT_SYMBOL(drm_kms_helper_poll_fini);

static void drm_kms_helper_poll_init_release(struct drm_device *dev, void *res)
{
        drm_kms_helper_poll_fini(dev);
}

/**
 * drmm_kms_helper_poll_init - initialize and enable output polling
 * @dev: drm_device
 *
 * This function initializes and then also enables output polling support for
 * @dev similar to drm_kms_helper_poll_init(). Polling will automatically be
 * cleaned up when the DRM device goes away.
 *
 * See drm_kms_helper_poll_init() for more information.
 */
void drmm_kms_helper_poll_init(struct drm_device *dev)
{
        int ret;

        drm_kms_helper_poll_init(dev);

        ret = drmm_add_action_or_reset(dev, drm_kms_helper_poll_init_release, dev);
        if (ret)
                drm_warn(dev, "Connector status will not be updated, error %d\n", ret);
}
EXPORT_SYMBOL(drmm_kms_helper_poll_init);

static bool check_connector_changed(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        enum drm_connector_status old_status;
        u64 old_epoch_counter;

        /* Only handle HPD capable connectors. */
        drm_WARN_ON(dev, !(connector->polled & DRM_CONNECTOR_POLL_HPD));

        drm_WARN_ON(dev, !mutex_is_locked(&dev->mode_config.mutex));

        old_status = connector->status;
        old_epoch_counter = connector->epoch_counter;
        connector->status = drm_helper_probe_detect(connector, NULL, false);

        if (old_epoch_counter == connector->epoch_counter) {
                drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Same epoch counter %llu\n",
                            connector->base.id,
                            connector->name,
                            connector->epoch_counter);

                return false;
        }

        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s\n",
                    connector->base.id,
                    connector->name,
                    drm_get_connector_status_name(old_status),
                    drm_get_connector_status_name(connector->status));

        drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Changed epoch counter %llu => %llu\n",
                    connector->base.id,
                    connector->name,
                    old_epoch_counter,
                    connector->epoch_counter);

        return true;
}

/**
 * drm_connector_helper_hpd_irq_event - hotplug processing
 * @connector: drm_connector
 *
 * Drivers can use this helper function to run a detect cycle on a connector
 * which has the DRM_CONNECTOR_POLL_HPD flag set in its &polled member.
 *
 * This helper function is useful for drivers which can track hotplug
 * interrupts for a single connector. Drivers that want to send a
 * hotplug event for all connectors or can't track hotplug interrupts
 * per connector need to use drm_helper_hpd_irq_event().
 *
 * This function must be called from process context with no mode
 * setting locks held.
 *
 * Note that a connector can be both polled and probed from the hotplug
 * handler, in case the hotplug interrupt is known to be unreliable.
 *
 * Returns:
 * A boolean indicating whether the connector status changed or not
 */
bool drm_connector_helper_hpd_irq_event(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        bool changed;

        mutex_lock(&dev->mode_config.mutex);
        changed = check_connector_changed(connector);
        mutex_unlock(&dev->mode_config.mutex);

        if (changed) {
                drm_kms_helper_connector_hotplug_event(connector);
                drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Sent hotplug event\n",
                            connector->base.id,
                            connector->name);
        }

        return changed;
}
EXPORT_SYMBOL(drm_connector_helper_hpd_irq_event);

/**
 * drm_helper_hpd_irq_event - hotplug processing
 * @dev: drm_device
 *
 * Drivers can use this helper function to run a detect cycle on all connectors
 * which have the DRM_CONNECTOR_POLL_HPD flag set in their &polled member. All
 * other connectors are ignored, which is useful to avoid reprobing fixed
 * panels.
 *
 * This helper function is useful for drivers which can't or don't track hotplug
 * interrupts for each connector.
 *
 * Drivers which support hotplug interrupts for each connector individually and
 * which have a more fine-grained detect logic can use
 * drm_connector_helper_hpd_irq_event(). Alternatively, they should bypass this
 * code and directly call drm_kms_helper_hotplug_event() in case the connector
 * state changed.
 *
 * This function must be called from process context with no mode
 * setting locks held.
 *
 * Note that a connector can be both polled and probed from the hotplug handler,
 * in case the hotplug interrupt is known to be unreliable.
 *
 * Returns:
 * A boolean indicating whether the connector status changed or not
 */
bool drm_helper_hpd_irq_event(struct drm_device *dev)
{
        struct drm_connector *connector, *first_changed_connector = NULL;
        struct drm_connector_list_iter conn_iter;
        int changed = 0;

        if (!dev->mode_config.poll_enabled)
                return false;

        mutex_lock(&dev->mode_config.mutex);
        drm_connector_list_iter_begin(dev, &conn_iter);
        drm_for_each_connector_iter(connector, &conn_iter) {
                /* Only handle HPD capable connectors. */
                if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
                        continue;

                if (check_connector_changed(connector)) {
                        if (!first_changed_connector) {
                                drm_connector_get(connector);
                                first_changed_connector = connector;
                        }

                        changed++;
                }
        }
        drm_connector_list_iter_end(&conn_iter);
        mutex_unlock(&dev->mode_config.mutex);

        if (changed == 1)
                drm_kms_helper_connector_hotplug_event(first_changed_connector);
        else if (changed > 0)
                drm_kms_helper_hotplug_event(dev);

        if (first_changed_connector)
                drm_connector_put(first_changed_connector);

        return changed;
}
EXPORT_SYMBOL(drm_helper_hpd_irq_event);

/**
 * drm_crtc_helper_mode_valid_fixed - Validates a display mode
 * @crtc: the crtc
 * @mode: the mode to validate
 * @fixed_mode: the display hardware's mode
 *
 * Returns:
 * MODE_OK on success, or another mode-status code otherwise.
 */
enum drm_mode_status drm_crtc_helper_mode_valid_fixed(struct drm_crtc *crtc,
                                                      const struct drm_display_mode *mode,
                                                      const struct drm_display_mode *fixed_mode)
{
        if (mode->hdisplay != fixed_mode->hdisplay && mode->vdisplay != fixed_mode->vdisplay)
                return MODE_ONE_SIZE;
        else if (mode->hdisplay != fixed_mode->hdisplay)
                return MODE_ONE_WIDTH;
        else if (mode->vdisplay != fixed_mode->vdisplay)
                return MODE_ONE_HEIGHT;

        return MODE_OK;
}
EXPORT_SYMBOL(drm_crtc_helper_mode_valid_fixed);

/**
 * drm_connector_helper_get_modes_fixed - Duplicates a display mode for a connector
 * @connector: the connector
 * @fixed_mode: the display hardware's mode
 *
 * This function duplicates a display modes for a connector. Drivers for hardware
 * that only supports a single fixed mode can use this function in their connector's
 * get_modes helper.
 *
 * Returns:
 * The number of created modes.
 */
int drm_connector_helper_get_modes_fixed(struct drm_connector *connector,
                                         const struct drm_display_mode *fixed_mode)
{
        struct drm_device *dev = connector->dev;
        struct drm_display_mode *mode;

        mode = drm_mode_duplicate(dev, fixed_mode);
        if (!mode) {
                drm_err(dev, "Failed to duplicate mode " DRM_MODE_FMT "\n",
                        DRM_MODE_ARG(fixed_mode));
                return 0;
        }

        if (mode->name[0] == '\0')
                drm_mode_set_name(mode);

        mode->type |= DRM_MODE_TYPE_PREFERRED;
        drm_mode_probed_add(connector, mode);

        if (mode->width_mm)
                connector->display_info.width_mm = mode->width_mm;
        if (mode->height_mm)
                connector->display_info.height_mm = mode->height_mm;

        return 1;
}
EXPORT_SYMBOL(drm_connector_helper_get_modes_fixed);

/**
 * drm_connector_helper_get_modes - Read EDID and update connector.
 * @connector: The connector
 *
 * Read the EDID using drm_edid_read() (which requires that connector->ddc is
 * set), and update the connector using the EDID.
 *
 * This can be used as the "default" connector helper .get_modes() hook if the
 * driver does not need any special processing. This is sets the example what
 * custom .get_modes() hooks should do regarding EDID read and connector update.
 *
 * Returns: Number of modes.
 */
int drm_connector_helper_get_modes(struct drm_connector *connector)
{
        const struct drm_edid *drm_edid;
        int count;

        drm_edid = drm_edid_read(connector);

        /*
         * Unconditionally update the connector. If the EDID was read
         * successfully, fill in the connector information derived from the
         * EDID. Otherwise, if the EDID is NULL, clear the connector
         * information.
         */
        drm_edid_connector_update(connector, drm_edid);

        count = drm_edid_connector_add_modes(connector);

        drm_edid_free(drm_edid);

        return count;
}
EXPORT_SYMBOL(drm_connector_helper_get_modes);

/**
 * drm_connector_helper_tv_get_modes - Fills the modes availables to a TV connector
 * @connector: The connector
 *
 * Fills the available modes for a TV connector based on the supported
 * TV modes, and the default mode expressed by the kernel command line.
 *
 * This can be used as the default TV connector helper .get_modes() hook
 * if the driver does not need any special processing.
 *
 * Returns:
 * The number of modes added to the connector.
 */
int drm_connector_helper_tv_get_modes(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct drm_property *tv_mode_property =
                dev->mode_config.tv_mode_property;
        struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
        unsigned int ntsc_modes = BIT(DRM_MODE_TV_MODE_NTSC) |
                BIT(DRM_MODE_TV_MODE_NTSC_443) |
                BIT(DRM_MODE_TV_MODE_NTSC_J) |
                BIT(DRM_MODE_TV_MODE_PAL_M);
        unsigned int pal_modes = BIT(DRM_MODE_TV_MODE_PAL) |
                BIT(DRM_MODE_TV_MODE_PAL_N) |
                BIT(DRM_MODE_TV_MODE_SECAM);
        unsigned int tv_modes[2] = { UINT_MAX, UINT_MAX };
        unsigned int i, supported_tv_modes = 0;

        if (!tv_mode_property)
                return 0;

        for (i = 0; i < tv_mode_property->num_values; i++)
                supported_tv_modes |= BIT(tv_mode_property->values[i]);

        if (((supported_tv_modes & ntsc_modes) &&
             (supported_tv_modes & pal_modes)) ||
            (supported_tv_modes & BIT(DRM_MODE_TV_MODE_MONOCHROME))) {
                uint64_t default_mode;

                if (drm_object_property_get_default_value(&connector->base,
                                                          tv_mode_property,
                                                          &default_mode))
                        return 0;

                if (cmdline->tv_mode_specified)
                        default_mode = cmdline->tv_mode;

                if (BIT(default_mode) & ntsc_modes) {
                        tv_modes[0] = DRM_MODE_TV_MODE_NTSC;
                        tv_modes[1] = DRM_MODE_TV_MODE_PAL;
                } else {
                        tv_modes[0] = DRM_MODE_TV_MODE_PAL;
                        tv_modes[1] = DRM_MODE_TV_MODE_NTSC;
                }
        } else if (supported_tv_modes & ntsc_modes) {
                tv_modes[0] = DRM_MODE_TV_MODE_NTSC;
        } else if (supported_tv_modes & pal_modes) {
                tv_modes[0] = DRM_MODE_TV_MODE_PAL;
        } else {
                return 0;
        }

        for (i = 0; i < ARRAY_SIZE(tv_modes); i++) {
                struct drm_display_mode *mode;

                if (tv_modes[i] == DRM_MODE_TV_MODE_NTSC)
                        mode = drm_mode_analog_ntsc_480i(dev);
                else if (tv_modes[i] == DRM_MODE_TV_MODE_PAL)
                        mode = drm_mode_analog_pal_576i(dev);
                else
                        break;
                if (!mode)
                        return i;
                if (!i)
                        mode->type |= DRM_MODE_TYPE_PREFERRED;
                drm_mode_probed_add(connector, mode);
        }

        return i;
}
EXPORT_SYMBOL(drm_connector_helper_tv_get_modes);

/**
 * drm_connector_helper_detect_from_ddc - Read EDID and detect connector status.
 * @connector: The connector
 * @ctx: Acquire context
 * @force: Perform screen-destructive operations, if necessary
 *
 * Detects the connector status by reading the EDID using drm_probe_ddc(),
 * which requires connector->ddc to be set. Returns connector_status_connected
 * on success or connector_status_disconnected on failure.
 *
 * Returns:
 * The connector status as defined by enum drm_connector_status.
 */
int drm_connector_helper_detect_from_ddc(struct drm_connector *connector,
                                         struct drm_modeset_acquire_ctx *ctx,
                                         bool force)
{
        struct i2c_adapter *ddc = connector->ddc;

        if (!ddc)
                return connector_status_unknown;

        if (drm_probe_ddc(ddc))
                return connector_status_connected;

        return connector_status_disconnected;
}
EXPORT_SYMBOL(drm_connector_helper_detect_from_ddc);