drm/radeon: rework page flip handling v3

Instead of trying to flip inside the vblank period when
the buffer is idle, offload blocking for idle to a kernel
thread and program the flip directly into the hardware.

v2: add error handling, fix EBUSY handling
v3: add proper exclusive_lock handling

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 150 insertions, 115 deletions

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 4ae304d7e932..736bfa2c7528 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -676,14 +676,16 @@ void radeon_doorbell_free(struct radeon_device *rdev, u32 doorbell);
  * IRQS.
  */
 
-struct radeon_unpin_work {
-        struct work_struct work;
-        struct radeon_device *rdev;
-        int crtc_id;
-        struct radeon_fence *fence;
+struct radeon_flip_work {
+        struct work_struct              flip_work;
+        struct work_struct              unpin_work;
+        struct radeon_device            *rdev;
+        int                             crtc_id;
+        struct drm_framebuffer          *fb;
         struct drm_pending_vblank_event *event;
-        struct radeon_bo *old_rbo;
-        u64 new_crtc_base;
+        struct radeon_bo                *old_rbo;
+        struct radeon_bo                *new_rbo;
+        struct radeon_fence             *fence;
 };
 
 struct r500_irq_stat_regs {
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 88e3cbe11dad..6b3de5ca5bc7 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -249,16 +249,21 @@ static void radeon_crtc_destroy(struct drm_crtc *crtc)
         struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
 
         drm_crtc_cleanup(crtc);
+        destroy_workqueue(radeon_crtc->flip_queue);
         kfree(radeon_crtc);
 }
 
-/*
- * Handle unpin events outside the interrupt handler proper.
+/**
+ * radeon_unpin_work_func - unpin old buffer object
+ *
+ * @__work - kernel work item
+ *
+ * Unpin the old frame buffer object outside of the interrupt handler
  */
 static void radeon_unpin_work_func(struct work_struct *__work)
 {
-        struct radeon_unpin_work *work =
-                container_of(__work, struct radeon_unpin_work, work);
+        struct radeon_flip_work *work =
+                container_of(__work, struct radeon_flip_work, unpin_work);
         int r;
 
         /* unpin of the old buffer */
@@ -279,30 +284,19 @@ static void radeon_unpin_work_func(struct work_struct *__work)
 void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
 {
         struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
-        struct radeon_unpin_work *work;
+        struct radeon_flip_work *work;
         unsigned long flags;
         u32 update_pending;
         int vpos, hpos;
 
         spin_lock_irqsave(&rdev->ddev->event_lock, flags);
-        work = radeon_crtc->unpin_work;
-        if (work == NULL ||
-            (work->fence && !radeon_fence_signaled(work->fence))) {
+        work = radeon_crtc->flip_work;
+        if (work == NULL) {
                 spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
                 return;
         }
-        /* New pageflip, or just completion of a previous one? */
-        if (!radeon_crtc->deferred_flip_completion) {
-                /* do the flip (mmio) */
-                radeon_page_flip(rdev, crtc_id, work->new_crtc_base);
-                update_pending = radeon_page_flip_pending(rdev, crtc_id);
-        } else {
-                /* This is just a completion of a flip queued in crtc
-                 * at last invocation. Make sure we go directly to
-                 * completion routine.
-                 */
-                update_pending = 0;
-        }
+
+        update_pending = radeon_page_flip_pending(rdev, crtc_id);
 
         /* Has the pageflip already completed in crtc, or is it certain
          * to complete in this vblank?
@@ -320,19 +314,9 @@ void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
                  */
                 update_pending = 0;
         }
-        if (update_pending) {
-                /* crtc didn't flip in this target vblank interval,
-                 * but flip is pending in crtc. It will complete it
-                 * in next vblank interval, so complete the flip at
-                 * next vblank irq.
-                 */
-                radeon_crtc->deferred_flip_completion = 1;
-                spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
-                return;
-        } else {
-                spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
+        spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
+        if (!update_pending)
                 radeon_crtc_handle_flip(rdev, crtc_id);
-        }
 }
 
 /**
@@ -346,7 +330,7 @@ void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
 void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
 {
         struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
-        struct radeon_unpin_work *work;
+        struct radeon_flip_work *work;
         unsigned long flags;
 
         /* this can happen at init */
@@ -354,15 +338,14 @@ void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
                 return;
 
         spin_lock_irqsave(&rdev->ddev->event_lock, flags);
-        work = radeon_crtc->unpin_work;
+        work = radeon_crtc->flip_work;
         if (work == NULL) {
                 spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
                 return;
         }
 
-        /* Pageflip (will be) certainly completed in this vblank. Clean up. */
-        radeon_crtc->unpin_work = NULL;
-        radeon_crtc->deferred_flip_completion = 0;
+        /* Pageflip completed. Clean up. */
+        radeon_crtc->flip_work = NULL;
 
         /* wakeup userspace */
         if (work->event)
@@ -372,83 +355,69 @@ void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
 
         radeon_fence_unref(&work->fence);
         radeon_irq_kms_pflip_irq_get(rdev, work->crtc_id);
-        schedule_work(&work->work);
+        queue_work(radeon_crtc->flip_queue, &work->unpin_work);
 }
 
-static int radeon_crtc_page_flip(struct drm_crtc *crtc,
-                                 struct drm_framebuffer *fb,
-                                 struct drm_pending_vblank_event *event,
-                                 uint32_t page_flip_flags)
+/**
+ * radeon_flip_work_func - page flip framebuffer
+ *
+ * @work - kernel work item
+ *
+ * Wait for the buffer object to become idle and do the actual page flip
+ */
+static void radeon_flip_work_func(struct work_struct *__work)
 {
-        struct drm_device *dev = crtc->dev;
-        struct radeon_device *rdev = dev->dev_private;
-        struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
-        struct radeon_framebuffer *old_radeon_fb;
-        struct radeon_framebuffer *new_radeon_fb;
-        struct drm_gem_object *obj;
-        struct radeon_bo *rbo;
-        struct radeon_unpin_work *work;
-        unsigned long flags;
-        u32 tiling_flags, pitch_pixels;
-        u64 base;
-        int r;
+        struct radeon_flip_work *work =
+                container_of(__work, struct radeon_flip_work, flip_work);
+        struct radeon_device *rdev = work->rdev;
+        struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[work->crtc_id];
 
-        work = kzalloc(sizeof *work, GFP_KERNEL);
-        if (work == NULL)
-                return -ENOMEM;
+        struct drm_crtc *crtc = &radeon_crtc->base;
+        struct drm_framebuffer *fb = work->fb;
 
-        work->event = event;
-        work->rdev = rdev;
-        work->crtc_id = radeon_crtc->crtc_id;
-        old_radeon_fb = to_radeon_framebuffer(crtc->primary->fb);
-        new_radeon_fb = to_radeon_framebuffer(fb);
-        /* schedule unpin of the old buffer */
-        obj = old_radeon_fb->obj;
-        /* take a reference to the old object */
-        drm_gem_object_reference(obj);
-        rbo = gem_to_radeon_bo(obj);
-        work->old_rbo = rbo;
-        obj = new_radeon_fb->obj;
-        rbo = gem_to_radeon_bo(obj);
+        uint32_t tiling_flags, pitch_pixels;
+        uint64_t base;
 
-        spin_lock(&rbo->tbo.bdev->fence_lock);
-        if (rbo->tbo.sync_obj)
-                work->fence = radeon_fence_ref(rbo->tbo.sync_obj);
-        spin_unlock(&rbo->tbo.bdev->fence_lock);
+        unsigned long flags;
+        int r;
 
-        INIT_WORK(&work->work, radeon_unpin_work_func);
+        down_read(&rdev->exclusive_lock);
+        while (work->fence) {
+                r = radeon_fence_wait(work->fence, false);
+                if (r == -EDEADLK) {
+                        up_read(&rdev->exclusive_lock);
+                        r = radeon_gpu_reset(rdev);
+                        down_read(&rdev->exclusive_lock);
+                }
 
-        /* We borrow the event spin lock for protecting unpin_work */
-        spin_lock_irqsave(&dev->event_lock, flags);
-        if (radeon_crtc->unpin_work) {
-                DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
-                r = -EBUSY;
-                goto unlock_free;
+                if (r) {
+                        DRM_ERROR("failed to wait on page flip fence (%d)!\n",
+                                  r);
+                        goto cleanup;
+                } else
+                        radeon_fence_unref(&work->fence);
         }
-        radeon_crtc->unpin_work = work;
-        radeon_crtc->deferred_flip_completion = 0;
-        spin_unlock_irqrestore(&dev->event_lock, flags);
 
         /* pin the new buffer */
         DRM_DEBUG_DRIVER("flip-ioctl() cur_fbo = %p, cur_bbo = %p\n",
-                         work->old_rbo, rbo);
+                         work->old_rbo, work->new_rbo);
 
-        r = radeon_bo_reserve(rbo, false);
+        r = radeon_bo_reserve(work->new_rbo, false);
         if (unlikely(r != 0)) {
                 DRM_ERROR("failed to reserve new rbo buffer before flip\n");
-                goto pflip_cleanup;
+                goto cleanup;
         }
         /* Only 27 bit offset for legacy CRTC */
-        r = radeon_bo_pin_restricted(rbo, RADEON_GEM_DOMAIN_VRAM,
+        r = radeon_bo_pin_restricted(work->new_rbo, RADEON_GEM_DOMAIN_VRAM,
                                      ASIC_IS_AVIVO(rdev) ? 0 : 1 << 27, &base);
         if (unlikely(r != 0)) {
-                radeon_bo_unreserve(rbo);
+                radeon_bo_unreserve(work->new_rbo);
                 r = -EINVAL;
                 DRM_ERROR("failed to pin new rbo buffer before flip\n");
-                goto pflip_cleanup;
+                goto cleanup;
         }
-        radeon_bo_get_tiling_flags(rbo, &tiling_flags, NULL);
-        radeon_bo_unreserve(rbo);
+        radeon_bo_get_tiling_flags(work->new_rbo, &tiling_flags, NULL);
+        radeon_bo_unreserve(work->new_rbo);
 
         if (!ASIC_IS_AVIVO(rdev)) {
                 /* crtc offset is from display base addr not FB location */
@@ -486,28 +455,91 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
                 base &= ~7;
         }
 
-        spin_lock_irqsave(&dev->event_lock, flags);
-        work->new_crtc_base = base;
-        spin_unlock_irqrestore(&dev->event_lock, flags);
-
-        /* update crtc fb */
-        crtc->primary->fb = fb;
+        /* We borrow the event spin lock for protecting flip_work */
+        spin_lock_irqsave(&crtc->dev->event_lock, flags);
 
         /* set the proper interrupt */
         radeon_irq_kms_pflip_irq_get(rdev, radeon_crtc->crtc_id);
 
-        return 0;
+        /* do the flip (mmio) */
+        radeon_page_flip(rdev, radeon_crtc->crtc_id, base);
 
-pflip_cleanup:
-        spin_lock_irqsave(&dev->event_lock, flags);
-        radeon_crtc->unpin_work = NULL;
-unlock_free:
-        spin_unlock_irqrestore(&dev->event_lock, flags);
-        drm_gem_object_unreference_unlocked(old_radeon_fb->obj);
+        spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
+        up_read(&rdev->exclusive_lock);
+
+        return;
+
+cleanup:
+        drm_gem_object_unreference_unlocked(&work->old_rbo->gem_base);
         radeon_fence_unref(&work->fence);
         kfree(work);
+        up_read(&rdev->exclusive_lock);
+}
+
+static int radeon_crtc_page_flip(struct drm_crtc *crtc,
+                                 struct drm_framebuffer *fb,
+                                 struct drm_pending_vblank_event *event,
+                                 uint32_t page_flip_flags)
+{
+        struct drm_device *dev = crtc->dev;
+        struct radeon_device *rdev = dev->dev_private;
+        struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
+        struct radeon_framebuffer *old_radeon_fb;
+        struct radeon_framebuffer *new_radeon_fb;
+        struct drm_gem_object *obj;
+        struct radeon_flip_work *work;
+        unsigned long flags;
+
+        work = kzalloc(sizeof *work, GFP_KERNEL);
+        if (work == NULL)
+                return -ENOMEM;
+
+        INIT_WORK(&work->flip_work, radeon_flip_work_func);
+        INIT_WORK(&work->unpin_work, radeon_unpin_work_func);
 
-        return r;
+        work->rdev = rdev;
+        work->crtc_id = radeon_crtc->crtc_id;
+        work->fb = fb;
+        work->event = event;
+
+        /* schedule unpin of the old buffer */
+        old_radeon_fb = to_radeon_framebuffer(crtc->primary->fb);
+        obj = old_radeon_fb->obj;
+
+        /* take a reference to the old object */
+        drm_gem_object_reference(obj);
+        work->old_rbo = gem_to_radeon_bo(obj);
+
+        new_radeon_fb = to_radeon_framebuffer(fb);
+        obj = new_radeon_fb->obj;
+        work->new_rbo = gem_to_radeon_bo(obj);
+
+        spin_lock(&work->new_rbo->tbo.bdev->fence_lock);
+        if (work->new_rbo->tbo.sync_obj)
+                work->fence = radeon_fence_ref(work->new_rbo->tbo.sync_obj);
+        spin_unlock(&work->new_rbo->tbo.bdev->fence_lock);
+
+        /* update crtc fb */
+        crtc->primary->fb = fb;
+
+        /* We borrow the event spin lock for protecting flip_work */
+        spin_lock_irqsave(&crtc->dev->event_lock, flags);
+
+        if (radeon_crtc->flip_work) {
+                DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
+                spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
+                drm_gem_object_unreference_unlocked(&work->old_rbo->gem_base);
+                radeon_fence_unref(&work->fence);
+                kfree(work);
+                return -EBUSY;
+        }
+        radeon_crtc->flip_work = work;
+
+        spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
+
+        queue_work(radeon_crtc->flip_queue, &work->flip_work);
+
+        return 0;
 }
 
 static int
@@ -577,6 +609,7 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
 
         drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
         radeon_crtc->crtc_id = index;
+        radeon_crtc->flip_queue = create_singlethread_workqueue("radeon-crtc");
         rdev->mode_info.crtcs[index] = radeon_crtc;
 
         if (rdev->family >= CHIP_BONAIRE) {
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 718be1a932ac..ea72ad889a11 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -325,8 +325,8 @@ struct radeon_crtc {
         struct drm_display_mode native_mode;
         int pll_id;
         /* page flipping */
-        struct radeon_unpin_work *unpin_work;
-        int deferred_flip_completion;
+        struct workqueue_struct *flip_queue;
+        struct radeon_flip_work *flip_work;
         /* pll sharing */
         struct radeon_atom_ss ss;
         bool ss_enabled;