// SPDX-License-Identifier: MIT
#include <linux/debugfs.h>
#include <linux/string.h>

#include <drm/drm_crtc.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_vblank.h>
#include <drm/drm_vblank_work.h>

#include <nvif/class.h>
#include <nvif/cl0002.h>
#include <nvif/timer.h>

#include <nvhw/class/cl907d.h>

#include "nouveau_drv.h"
#include "core.h"
#include "head.h"
#include "wndw.h"
#include "handles.h"
#include "crc.h"

static const char * const nv50_crc_sources[] = {
        [NV50_CRC_SOURCE_NONE] = "none",
        [NV50_CRC_SOURCE_AUTO] = "auto",
        [NV50_CRC_SOURCE_RG] = "rg",
        [NV50_CRC_SOURCE_OUTP_ACTIVE] = "outp-active",
        [NV50_CRC_SOURCE_OUTP_COMPLETE] = "outp-complete",
        [NV50_CRC_SOURCE_OUTP_INACTIVE] = "outp-inactive",
};

static int nv50_crc_parse_source(const char *buf, enum nv50_crc_source *s)
{
        int i;

        if (!buf) {
                *s = NV50_CRC_SOURCE_NONE;
                return 0;
        }

        i = match_string(nv50_crc_sources, ARRAY_SIZE(nv50_crc_sources), buf);
        if (i < 0)
                return i;

        *s = i;
        return 0;
}

int
nv50_crc_verify_source(struct drm_crtc *crtc, const char *source_name,
                       size_t *values_cnt)
{
        struct nouveau_drm *drm = nouveau_drm(crtc->dev);
        enum nv50_crc_source source;

        if (nv50_crc_parse_source(source_name, &source) < 0) {
                NV_DEBUG(drm, "unknown source %s\n", source_name);
                return -EINVAL;
        }

        *values_cnt = 1;
        return 0;
}

const char *const *nv50_crc_get_sources(struct drm_crtc *crtc, size_t *count)
{
        *count = ARRAY_SIZE(nv50_crc_sources);
        return nv50_crc_sources;
}

static void
nv50_crc_program_ctx(struct nv50_head *head,
                     struct nv50_crc_notifier_ctx *ctx)
{
        struct nv50_disp *disp = nv50_disp(head->base.base.dev);
        struct nv50_core *core = disp->core;
        u32 interlock[NV50_DISP_INTERLOCK__SIZE] = { 0 };

        core->func->crc->set_ctx(head, ctx);
        core->func->update(core, interlock, false);
}

static void nv50_crc_ctx_flip_work(struct kthread_work *base)
{
        struct drm_vblank_work *work = to_drm_vblank_work(base);
        struct nv50_crc *crc = container_of(work, struct nv50_crc, flip_work);
        struct nv50_head *head = container_of(crc, struct nv50_head, crc);
        struct drm_crtc *crtc = &head->base.base;
        struct drm_device *dev = crtc->dev;
        struct nv50_disp *disp = nv50_disp(dev);
        const uint64_t start_vbl = drm_crtc_vblank_count(crtc);
        uint64_t end_vbl;
        u8 new_idx = crc->ctx_idx ^ 1;

        /*
         * We don't want to accidentally wait for longer then the vblank, so
         * try again for the next vblank if we don't grab the lock
         */
        if (!mutex_trylock(&disp->mutex)) {
                drm_dbg_kms(dev, "Lock contended, delaying CRC ctx flip for %s\n", crtc->name);
                drm_vblank_work_schedule(work, start_vbl + 1, true);
                return;
        }

        drm_dbg_kms(dev, "Flipping notifier ctx for %s (%d -> %d)\n",
                    crtc->name, crc->ctx_idx, new_idx);

        nv50_crc_program_ctx(head, NULL);
        nv50_crc_program_ctx(head, &crc->ctx[new_idx]);
        mutex_unlock(&disp->mutex);

        end_vbl = drm_crtc_vblank_count(crtc);
        if (unlikely(end_vbl != start_vbl))
                NV_ERROR(nouveau_drm(dev),
                         "Failed to flip CRC context on %s on time (%llu > %llu)\n",
                         crtc->name, end_vbl, start_vbl);

        spin_lock_irq(&crc->lock);
        crc->ctx_changed = true;
        spin_unlock_irq(&crc->lock);
}

static inline void nv50_crc_reset_ctx(struct nv50_crc_notifier_ctx *ctx)
{
        memset_io(ctx->mem.object.map.ptr, 0, ctx->mem.object.map.size);
}

static void
nv50_crc_get_entries(struct nv50_head *head,
                     const struct nv50_crc_func *func,
                     enum nv50_crc_source source)
{
        struct drm_crtc *crtc = &head->base.base;
        struct nv50_crc *crc = &head->crc;
        u32 output_crc;

        while (crc->entry_idx < func->num_entries) {
                /*
                 * While Nvidia's documentation says CRCs are written on each
                 * subsequent vblank after being enabled, in practice they
                 * aren't written immediately.
                 */
                output_crc = func->get_entry(head, &crc->ctx[crc->ctx_idx],
                                             source, crc->entry_idx);
                if (!output_crc)
                        return;

                drm_crtc_add_crc_entry(crtc, true, crc->frame, &output_crc);
                crc->frame++;
                crc->entry_idx++;
        }
}

void nv50_crc_handle_vblank(struct nv50_head *head)
{
        struct drm_crtc *crtc = &head->base.base;
        struct nv50_crc *crc = &head->crc;
        const struct nv50_crc_func *func =
                nv50_disp(head->base.base.dev)->core->func->crc;
        struct nv50_crc_notifier_ctx *ctx;
        bool need_reschedule = false;

        if (!func)
                return;

        /*
         * We don't lose events if we aren't able to report CRCs until the
         * next vblank, so only report CRCs if the locks we need aren't
         * contended to prevent missing an actual vblank event
         */
        if (!spin_trylock(&crc->lock))
                return;

        if (!crc->src)
                goto out;

        ctx = &crc->ctx[crc->ctx_idx];
        if (crc->ctx_changed && func->ctx_finished(head, ctx)) {
                nv50_crc_get_entries(head, func, crc->src);

                crc->ctx_idx ^= 1;
                crc->entry_idx = 0;
                crc->ctx_changed = false;

                /*
                 * Unfortunately when notifier contexts are changed during CRC
                 * capture, we will inevitably lose the CRC entry for the
                 * frame where the hardware actually latched onto the first
                 * UPDATE. According to Nvidia's hardware engineers, there's
                 * no workaround for this.
                 *
                 * Now, we could try to be smart here and calculate the number
                 * of missed CRCs based on audit timestamps, but those were
                 * removed starting with volta. Since we always flush our
                 * updates back-to-back without waiting, we'll just be
                 * optimistic and assume we always miss exactly one frame.
                 */
                drm_dbg_kms(head->base.base.dev,
                            "Notifier ctx flip for head-%d finished, lost CRC for frame %llu\n",
                            head->base.index, crc->frame);
                crc->frame++;

                nv50_crc_reset_ctx(ctx);
                need_reschedule = true;
        }

        nv50_crc_get_entries(head, func, crc->src);

        if (need_reschedule)
                drm_vblank_work_schedule(&crc->flip_work,
                                         drm_crtc_vblank_count(crtc)
                                         + crc->flip_threshold
                                         - crc->entry_idx,
                                         true);

out:
        spin_unlock(&crc->lock);
}

static void nv50_crc_wait_ctx_finished(struct nv50_head *head,
                                       const struct nv50_crc_func *func,
                                       struct nv50_crc_notifier_ctx *ctx)
{
        struct drm_device *dev = head->base.base.dev;
        struct nouveau_drm *drm = nouveau_drm(dev);
        s64 ret;

        ret = nvif_msec(&drm->client.device, 50,
                        if (func->ctx_finished(head, ctx)) break;);
        if (ret == -ETIMEDOUT)
                NV_ERROR(drm,
                         "CRC notifier ctx for head %d not finished after 50ms\n",
                         head->base.index);
        else if (ret)
                NV_ATOMIC(drm,
                          "CRC notifier ctx for head-%d finished after %lldns\n",
                          head->base.index, ret);
}

void nv50_crc_atomic_stop_reporting(struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        int i;

        for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
                struct nv50_head *head = nv50_head(crtc);
                struct nv50_head_atom *asyh = nv50_head_atom(crtc_state);
                struct nv50_crc *crc = &head->crc;

                if (!asyh->clr.crc)
                        continue;

                spin_lock_irq(&crc->lock);
                crc->src = NV50_CRC_SOURCE_NONE;
                spin_unlock_irq(&crc->lock);

                drm_crtc_vblank_put(crtc);
                drm_vblank_work_cancel_sync(&crc->flip_work);

                NV_ATOMIC(nouveau_drm(crtc->dev),
                          "CRC reporting on vblank for head-%d disabled\n",
                          head->base.index);

                /* CRC generation is still enabled in hw, we'll just report
                 * any remaining CRC entries ourselves after it gets disabled
                 * in hardware
                 */
        }
}

void nv50_crc_atomic_init_notifier_contexts(struct drm_atomic_state *state)
{
        struct drm_crtc_state *new_crtc_state;
        struct drm_crtc *crtc;
        int i;

        for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
                struct nv50_head *head = nv50_head(crtc);
                struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state);
                struct nv50_crc *crc = &head->crc;
                int i;

                if (!asyh->set.crc)
                        continue;

                crc->entry_idx = 0;
                crc->ctx_changed = false;
                for (i = 0; i < ARRAY_SIZE(crc->ctx); i++)
                        nv50_crc_reset_ctx(&crc->ctx[i]);
        }
}

void nv50_crc_atomic_release_notifier_contexts(struct drm_atomic_state *state)
{
        const struct nv50_crc_func *func =
                nv50_disp(state->dev)->core->func->crc;
        struct drm_crtc_state *new_crtc_state;
        struct drm_crtc *crtc;
        int i;

        for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
                struct nv50_head *head = nv50_head(crtc);
                struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state);
                struct nv50_crc *crc = &head->crc;
                struct nv50_crc_notifier_ctx *ctx = &crc->ctx[crc->ctx_idx];

                if (!asyh->clr.crc)
                        continue;

                if (crc->ctx_changed) {
                        nv50_crc_wait_ctx_finished(head, func, ctx);
                        ctx = &crc->ctx[crc->ctx_idx ^ 1];
                }
                nv50_crc_wait_ctx_finished(head, func, ctx);
        }
}

void nv50_crc_atomic_start_reporting(struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        int i;

        for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
                struct nv50_head *head = nv50_head(crtc);
                struct nv50_head_atom *asyh = nv50_head_atom(crtc_state);
                struct nv50_crc *crc = &head->crc;
                u64 vbl_count;

                if (!asyh->set.crc)
                        continue;

                drm_crtc_vblank_get(crtc);

                spin_lock_irq(&crc->lock);
                vbl_count = drm_crtc_vblank_count(crtc);
                crc->frame = vbl_count;
                crc->src = asyh->crc.src;
                drm_vblank_work_schedule(&crc->flip_work,
                                         vbl_count + crc->flip_threshold,
                                         true);
                spin_unlock_irq(&crc->lock);

                NV_ATOMIC(nouveau_drm(crtc->dev),
                          "CRC reporting on vblank for head-%d enabled\n",
                          head->base.index);
        }
}

int nv50_crc_atomic_check_head(struct nv50_head *head,
                               struct nv50_head_atom *asyh,
                               struct nv50_head_atom *armh)
{
        struct nv50_atom *atom = nv50_atom(asyh->state.state);
        bool changed = armh->crc.src != asyh->crc.src;

        if (!armh->crc.src && !asyh->crc.src) {
                asyh->set.crc = false;
                asyh->clr.crc = false;
                return 0;
        }

        if (drm_atomic_crtc_needs_modeset(&asyh->state) || changed) {
                asyh->clr.crc = armh->crc.src && armh->state.active;
                asyh->set.crc = asyh->crc.src && asyh->state.active;
                if (changed)
                        asyh->set.or |= armh->or.crc_raster !=
                                        asyh->or.crc_raster;

                if (asyh->clr.crc && asyh->set.crc)
                        atom->flush_disable = true;
        } else {
                asyh->set.crc = false;
                asyh->clr.crc = false;
        }

        return 0;
}

void nv50_crc_atomic_check_outp(struct nv50_atom *atom)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state, *new_crtc_state;
        int i;

        if (atom->flush_disable)
                return;

        for_each_oldnew_crtc_in_state(&atom->state, crtc, old_crtc_state,
                                      new_crtc_state, i) {
                struct nv50_head_atom *armh = nv50_head_atom(old_crtc_state);
                struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state);
                struct nv50_outp_atom *outp_atom;
                struct nouveau_encoder *outp;
                struct drm_encoder *encoder, *enc;

                enc = nv50_head_atom_get_encoder(armh);
                if (!enc)
                        continue;

                outp = nv50_real_outp(enc);
                if (!outp)
                        continue;

                encoder = &outp->base.base;

                if (!asyh->clr.crc)
                        continue;

                /*
                 * Re-programming ORs can't be done in the same flush as
                 * disabling CRCs
                 */
                list_for_each_entry(outp_atom, &atom->outp, head) {
                        if (outp_atom->encoder == encoder) {
                                if (outp_atom->set.mask) {
                                        atom->flush_disable = true;
                                        return;
                                } else {
                                        break;
                                }
                        }
                }
        }
}

static enum nv50_crc_source_type
nv50_crc_source_type(struct nouveau_encoder *outp,
                     enum nv50_crc_source source)
{
        struct dcb_output *dcbe = outp->dcb;

        switch (source) {
        case NV50_CRC_SOURCE_NONE: return NV50_CRC_SOURCE_TYPE_NONE;
        case NV50_CRC_SOURCE_RG:   return NV50_CRC_SOURCE_TYPE_RG;
        default:                   break;
        }

        if (dcbe->location != DCB_LOC_ON_CHIP)
                return NV50_CRC_SOURCE_TYPE_PIOR;

        switch (dcbe->type) {
        case DCB_OUTPUT_DP:     return NV50_CRC_SOURCE_TYPE_SF;
        case DCB_OUTPUT_ANALOG: return NV50_CRC_SOURCE_TYPE_DAC;
        default:                return NV50_CRC_SOURCE_TYPE_SOR;
        }
}

void nv50_crc_atomic_set(struct nv50_head *head,
                         struct nv50_head_atom *asyh)
{
        struct drm_crtc *crtc = &head->base.base;
        struct drm_device *dev = crtc->dev;
        struct nv50_crc *crc = &head->crc;
        const struct nv50_crc_func *func = nv50_disp(dev)->core->func->crc;
        struct nouveau_encoder *outp;
        struct drm_encoder *encoder;

        encoder = nv50_head_atom_get_encoder(asyh);
        if (!encoder)
                return;

        outp = nv50_real_outp(encoder);
        if (!outp)
                return;

        func->set_src(head, outp->outp.or.id, nv50_crc_source_type(outp, asyh->crc.src),
                      &crc->ctx[crc->ctx_idx]);
}

void nv50_crc_atomic_clr(struct nv50_head *head)
{
        const struct nv50_crc_func *func =
                nv50_disp(head->base.base.dev)->core->func->crc;

        func->set_src(head, 0, NV50_CRC_SOURCE_TYPE_NONE, NULL);
}

static inline int
nv50_crc_raster_type(enum nv50_crc_source source)
{
        switch (source) {
        case NV50_CRC_SOURCE_NONE:
        case NV50_CRC_SOURCE_AUTO:
        case NV50_CRC_SOURCE_RG:
        case NV50_CRC_SOURCE_OUTP_ACTIVE:
                return NV907D_HEAD_SET_CONTROL_OUTPUT_RESOURCE_CRC_MODE_ACTIVE_RASTER;
        case NV50_CRC_SOURCE_OUTP_COMPLETE:
                return NV907D_HEAD_SET_CONTROL_OUTPUT_RESOURCE_CRC_MODE_COMPLETE_RASTER;
        case NV50_CRC_SOURCE_OUTP_INACTIVE:
                return NV907D_HEAD_SET_CONTROL_OUTPUT_RESOURCE_CRC_MODE_NON_ACTIVE_RASTER;
        }

        return 0;
}

/* We handle mapping the memory for CRC notifiers ourselves, since each
 * notifier needs it's own handle
 */
static inline int
nv50_crc_ctx_init(struct nv50_head *head, struct nvif_mmu *mmu,
                  struct nv50_crc_notifier_ctx *ctx, size_t len, int idx)
{
        struct nv50_core *core = nv50_disp(head->base.base.dev)->core;
        int ret;

        ret = nvif_mem_ctor_map(mmu, "kmsCrcNtfy", NVIF_MEM_VRAM, len, &ctx->mem);
        if (ret)
                return ret;

        /* No CTXDMAs on Blackwell. */
        if (core->chan.base.user.oclass >= GB202_DISP_CORE_CHANNEL_DMA)
                return 0;

        ret = nvif_object_ctor(&core->chan.base.user, "kmsCrcNtfyCtxDma",
                               NV50_DISP_HANDLE_CRC_CTX(head, idx),
                               NV_DMA_IN_MEMORY,
                               &(struct nv_dma_v0) {
                                        .target = NV_DMA_V0_TARGET_VRAM,
                                        .access = NV_DMA_V0_ACCESS_RDWR,
                                        .start = ctx->mem.addr,
                                        .limit =  ctx->mem.addr
                                                + ctx->mem.size - 1,
                               }, sizeof(struct nv_dma_v0),
                               &ctx->ntfy);
        if (ret)
                goto fail_fini;

        return 0;

fail_fini:
        nvif_mem_dtor(&ctx->mem);
        return ret;
}

static inline void
nv50_crc_ctx_fini(struct nv50_crc_notifier_ctx *ctx)
{
        nvif_object_dtor(&ctx->ntfy);
        nvif_mem_dtor(&ctx->mem);
}

int nv50_crc_set_source(struct drm_crtc *crtc, const char *source_str)
{
        struct drm_device *dev = crtc->dev;
        struct drm_atomic_state *state;
        struct drm_modeset_acquire_ctx ctx;
        struct nv50_head *head = nv50_head(crtc);
        struct nv50_crc *crc = &head->crc;
        const struct nv50_crc_func *func = nv50_disp(dev)->core->func->crc;
        struct nvif_mmu *mmu = &nouveau_drm(dev)->client.mmu;
        struct nv50_head_atom *asyh;
        struct drm_crtc_state *crtc_state;
        enum nv50_crc_source source;
        int ret = 0, ctx_flags = 0, i;

        ret = nv50_crc_parse_source(source_str, &source);
        if (ret)
                return ret;

        /*
         * Since we don't want the user to accidentally interrupt us as we're
         * disabling CRCs
         */
        if (source)
                ctx_flags |= DRM_MODESET_ACQUIRE_INTERRUPTIBLE;
        drm_modeset_acquire_init(&ctx, ctx_flags);

        state = drm_atomic_state_alloc(dev);
        if (!state) {
                ret = -ENOMEM;
                goto out_acquire_fini;
        }
        state->acquire_ctx = &ctx;

        if (source) {
                for (i = 0; i < ARRAY_SIZE(head->crc.ctx); i++) {
                        ret = nv50_crc_ctx_init(head, mmu, &crc->ctx[i],
                                                func->notifier_len, i);
                        if (ret)
                                goto out_ctx_fini;
                }
        }

retry:
        crtc_state = drm_atomic_get_crtc_state(state, &head->base.base);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                if (ret == -EDEADLK)
                        goto deadlock;
                else if (ret)
                        goto out_drop_locks;
        }
        asyh = nv50_head_atom(crtc_state);
        asyh->crc.src = source;
        asyh->or.crc_raster = nv50_crc_raster_type(source);

        ret = drm_atomic_commit(state);
        if (ret == -EDEADLK)
                goto deadlock;
        else if (ret)
                goto out_drop_locks;

        if (!source) {
                /*
                 * If the user specified a custom flip threshold through
                 * debugfs, reset it
                 */
                crc->flip_threshold = func->flip_threshold;
        }

out_drop_locks:
        drm_modeset_drop_locks(&ctx);
out_ctx_fini:
        if (!source || ret) {
                for (i = 0; i < ARRAY_SIZE(crc->ctx); i++)
                        nv50_crc_ctx_fini(&crc->ctx[i]);
        }
        drm_atomic_state_put(state);
out_acquire_fini:
        drm_modeset_acquire_fini(&ctx);
        return ret;

deadlock:
        drm_atomic_state_clear(state);
        drm_modeset_backoff(&ctx);
        goto retry;
}

static int
nv50_crc_debugfs_flip_threshold_get(struct seq_file *m, void *data)
{
        struct nv50_head *head = m->private;
        struct drm_crtc *crtc = &head->base.base;
        struct nv50_crc *crc = &head->crc;
        int ret;

        ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
        if (ret)
                return ret;

        seq_printf(m, "%d\n", crc->flip_threshold);

        drm_modeset_unlock(&crtc->mutex);
        return ret;
}

static int
nv50_crc_debugfs_flip_threshold_open(struct inode *inode, struct file *file)
{
        return single_open(file, nv50_crc_debugfs_flip_threshold_get,
                           inode->i_private);
}

static ssize_t
nv50_crc_debugfs_flip_threshold_set(struct file *file,
                                    const char __user *ubuf, size_t len,
                                    loff_t *offp)
{
        struct seq_file *m = file->private_data;
        struct nv50_head *head = m->private;
        struct nv50_head_atom *armh;
        struct drm_crtc *crtc = &head->base.base;
        struct nouveau_drm *drm = nouveau_drm(crtc->dev);
        struct nv50_crc *crc = &head->crc;
        const struct nv50_crc_func *func =
                nv50_disp(crtc->dev)->core->func->crc;
        int value, ret;

        ret = kstrtoint_from_user(ubuf, len, 10, &value);
        if (ret)
                return ret;

        if (value > func->flip_threshold)
                return -EINVAL;
        else if (value == -1)
                value = func->flip_threshold;
        else if (value < -1)
                return -EINVAL;

        ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
        if (ret)
                return ret;

        armh = nv50_head_atom(crtc->state);
        if (armh->crc.src) {
                ret = -EBUSY;
                goto out;
        }

        NV_DEBUG(drm,
                 "Changing CRC flip threshold for next capture on head-%d to %d\n",
                 head->base.index, value);
        crc->flip_threshold = value;
        ret = len;

out:
        drm_modeset_unlock(&crtc->mutex);
        return ret;
}

static const struct file_operations nv50_crc_flip_threshold_fops = {
        .owner = THIS_MODULE,
        .open = nv50_crc_debugfs_flip_threshold_open,
        .read = seq_read,
        .write = nv50_crc_debugfs_flip_threshold_set,
        .release = single_release,
};

int nv50_head_crc_late_register(struct nv50_head *head)
{
        struct drm_crtc *crtc = &head->base.base;
        const struct nv50_crc_func *func =
                nv50_disp(crtc->dev)->core->func->crc;
        struct dentry *root;

        if (!func || !crtc->debugfs_entry)
                return 0;

        root = debugfs_create_dir("nv_crc", crtc->debugfs_entry);
        debugfs_create_file("flip_threshold", 0644, root, head,
                            &nv50_crc_flip_threshold_fops);

        return 0;
}

static inline void
nv50_crc_init_head(struct nv50_disp *disp, const struct nv50_crc_func *func,
                   struct nv50_head *head)
{
        struct nv50_crc *crc = &head->crc;

        crc->flip_threshold = func->flip_threshold;
        spin_lock_init(&crc->lock);
        drm_vblank_work_init(&crc->flip_work, &head->base.base,
                             nv50_crc_ctx_flip_work);
}

void nv50_crc_init(struct drm_device *dev)
{
        struct nv50_disp *disp = nv50_disp(dev);
        struct drm_crtc *crtc;
        const struct nv50_crc_func *func = disp->core->func->crc;

        if (!func)
                return;

        drm_for_each_crtc(crtc, dev)
                nv50_crc_init_head(disp, func, nv50_head(crtc));
}