Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3188a24c authored by Michel Dänzer's avatar Michel Dänzer Committed by Dave Airlie
Browse files

i915_vblank_tasklet: Try harder to avoid tearing. 



Previously, if there were several buffer swaps scheduled for the same vertical
blank, all but the first blit emitted stood a chance of exhibiting tearing. In
order to avoid this, split the blits along slices of each output top to bottom.

Signed-off-by: default avatarDave Airlie <airlied@linux.ie>
parent 2c3f0edd

drivers/char/drm/i915_irq.c

+139 −60
Original line number Diff line number Diff line
@@ -46,41 +46,82 @@ static void i915_vblank_tasklet(drm_device_t *dev) 
{

	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;

	unsigned long irqflags;

	struct list_head *list, *tmp;

	struct list_head *list, *tmp, hits, *hit;

	int nhits, nrects, slice[2], upper[2], lower[2], i;

	unsigned counter[2] = { atomic_read(&dev->vbl_received),

				atomic_read(&dev->vbl_received2) };

	drm_drawable_info_t *drw;

	drm_i915_sarea_t *sarea_priv = dev_priv->sarea_priv;

	u32 cpp = dev_priv->cpp;

	u32 cmd = (cpp == 4) ? (XY_SRC_COPY_BLT_CMD |

				XY_SRC_COPY_BLT_WRITE_ALPHA |

				XY_SRC_COPY_BLT_WRITE_RGB)

			     : XY_SRC_COPY_BLT_CMD;

	u32 pitchropcpp = (sarea_priv->pitch * cpp) | (0xcc << 16) |

			  (cpp << 23) | (1 << 24);

	RING_LOCALS;



	DRM_DEBUG("\n");



	INIT_LIST_HEAD(&hits);



	nhits = nrects = 0;



	spin_lock_irqsave(&dev_priv->swaps_lock, irqflags);



	/* Find buffer swaps scheduled for this vertical blank */

	list_for_each_safe(list, tmp, &dev_priv->vbl_swaps.head) {

		drm_i915_vbl_swap_t *vbl_swap =

			list_entry(list, drm_i915_vbl_swap_t, head);

		atomic_t *counter = vbl_swap->pipe ? &dev->vbl_received2 :

			&dev->vbl_received;



		if ((atomic_read(counter) - vbl_swap->sequence) <= (1<<23)) {

			drm_drawable_info_t *drw;

		if ((counter[vbl_swap->pipe] - vbl_swap->sequence) > (1<<23))

			continue;



			spin_unlock(&dev_priv->swaps_lock);

		list_del(list);

		dev_priv->swaps_pending--;



		spin_unlock(&dev_priv->swaps_lock);

		spin_lock(&dev->drw_lock);



		drw = drm_get_drawable_info(dev, vbl_swap->drw_id);



			if (drw) {

				int i, num_rects = drw->num_rects;

				drm_clip_rect_t *rect = drw->rects;

				drm_i915_sarea_t *sarea_priv =

				    dev_priv->sarea_priv;

				u32 cpp = dev_priv->cpp;

				u32 cmd = (cpp == 4) ? (XY_SRC_COPY_BLT_CMD |

							XY_SRC_COPY_BLT_WRITE_ALPHA |

							XY_SRC_COPY_BLT_WRITE_RGB)

						     : XY_SRC_COPY_BLT_CMD;

				u32 pitchropcpp = (sarea_priv->pitch * cpp) |

						  (0xcc << 16) | (cpp << 23) |

						  (1 << 24);

				RING_LOCALS;

		if (!drw) {

			spin_unlock(&dev->drw_lock);

			drm_free(vbl_swap, sizeof(*vbl_swap), DRM_MEM_DRIVER);

			spin_lock(&dev_priv->swaps_lock);

			continue;

		}



		list_for_each(hit, &hits) {

			drm_i915_vbl_swap_t *swap_cmp =

				list_entry(hit, drm_i915_vbl_swap_t, head);

			drm_drawable_info_t *drw_cmp =

				drm_get_drawable_info(dev, swap_cmp->drw_id);



			if (drw_cmp &&

			    drw_cmp->rects[0].y1 > drw->rects[0].y1) {

				list_add_tail(list, hit);

				break;

			}

		}



		spin_unlock(&dev->drw_lock);



		/* List of hits was empty, or we reached the end of it */

		if (hit == &hits)

			list_add_tail(list, hits.prev);



		nhits++;



		spin_lock(&dev_priv->swaps_lock);

	}



	if (nhits == 0) {

		spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);

		return;

	}



	spin_unlock(&dev_priv->swaps_lock);



	i915_kernel_lost_context(dev);
@@ -89,47 +130,85 @@ static void i915_vblank_tasklet(drm_device_t *dev) 
	OUT_RING(GFX_OP_DRAWRECT_INFO);

	OUT_RING(0);

	OUT_RING(0);

				OUT_RING(sarea_priv->width |

					 sarea_priv->height << 16);

				OUT_RING(sarea_priv->width |

					 sarea_priv->height << 16);

	OUT_RING(sarea_priv->width | sarea_priv->height << 16);

	OUT_RING(sarea_priv->width | sarea_priv->height << 16);

	OUT_RING(0);



	ADVANCE_LP_RING();



	sarea_priv->ctxOwner = DRM_KERNEL_CONTEXT;



				for (i = 0; i < num_rects; i++, rect++) {

	upper[0] = upper[1] = 0;

	slice[0] = max(sarea_priv->pipeA_h / nhits, 1);

	slice[1] = max(sarea_priv->pipeB_h / nhits, 1);

	lower[0] = sarea_priv->pipeA_y + slice[0];

	lower[1] = sarea_priv->pipeB_y + slice[0];



	spin_lock(&dev->drw_lock);



	/* Emit blits for buffer swaps, partitioning both outputs into as many

	 * slices as there are buffer swaps scheduled in order to avoid tearing

	 * (based on the assumption that a single buffer swap would always

	 * complete before scanout starts).

	 */

	for (i = 0; i++ < nhits;

	     upper[0] = lower[0], lower[0] += slice[0],

	     upper[1] = lower[1], lower[1] += slice[1]) {

		if (i == nhits)

			lower[0] = lower[1] = sarea_priv->height;



		list_for_each(hit, &hits) {

			drm_i915_vbl_swap_t *swap_hit =

				list_entry(hit, drm_i915_vbl_swap_t, head);

			drm_clip_rect_t *rect;

			int num_rects, pipe;

			unsigned short top, bottom;



			drw = drm_get_drawable_info(dev, swap_hit->drw_id);



			if (!drw)

				continue;



			rect = drw->rects;

			pipe = swap_hit->pipe;

			top = upper[pipe];

			bottom = lower[pipe];



			for (num_rects = drw->num_rects; num_rects--; rect++) {

				int y1 = max(rect->y1, top);

				int y2 = min(rect->y2, bottom);



				if (y1 >= y2)

					continue;



				BEGIN_LP_RING(8);



				OUT_RING(cmd);

				OUT_RING(pitchropcpp);

					OUT_RING((rect->y1 << 16) | rect->x1);

					OUT_RING((rect->y2 << 16) | rect->x2);

				OUT_RING((y1 << 16) | rect->x1);

				OUT_RING((y2 << 16) | rect->x2);

				OUT_RING(sarea_priv->front_offset);

					OUT_RING((rect->y1 << 16) | rect->x1);

				OUT_RING((y1 << 16) | rect->x1);

				OUT_RING(pitchropcpp & 0xffff);

				OUT_RING(sarea_priv->back_offset);



				ADVANCE_LP_RING();

			}

		}

	}



			spin_unlock(&dev->drw_lock);



			spin_lock(&dev_priv->swaps_lock);

	spin_unlock_irqrestore(&dev->drw_lock, irqflags);



			list_del(list);

	list_for_each_safe(hit, tmp, &hits) {

		drm_i915_vbl_swap_t *swap_hit =

			list_entry(hit, drm_i915_vbl_swap_t, head);



			drm_free(vbl_swap, sizeof(*vbl_swap), DRM_MEM_DRIVER);

		list_del(hit);



			dev_priv->swaps_pending--;

		drm_free(swap_hit, sizeof(*swap_hit), DRM_MEM_DRIVER);

	}

}



	spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);

}



irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)

{

	drm_device_t *dev = (drm_device_t *) arg;