drm/v3d: Add missing implicit synchronization.

It is the expectation of existing userspace (X11 + Mesa, in
particular) that jobs submitted to the kernel against a shared BO will
get implicitly synchronized by their submission order.  If we want to
allow clever userspace to disable implicit synchronization, we should
do that under its own submit flag (as amdgpu and lima do).

Note that we currently only implicitly sync for the rendering pass,
not binning -- if you texture-from-pixmap in the binning vertex shader
(vertex coordinate generation), you'll miss out on synchronization.

Fixes flickering when multiple clients are running in parallel,
particularly GL apps and compositors.

v2: Fix a missing refcount on the CSD done fence for L2 cleaning.

Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190416225856.20264-6-eric@anholt.net
Acked-by: Rob Clark <robdclark@gmail.com>

1 files changed, 4 insertions, 36 deletions

diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
index ad2245701dda..b4255807b3a7 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -74,47 +74,15 @@ v3d_job_dependency(struct drm_sched_job *sched_job,
 		   struct drm_sched_entity *s_entity)
 {
 	struct v3d_job *job = to_v3d_job(sched_job);
-	struct dma_fence *fence;
-
-	fence = job->in_fence;
-	if (fence) {
-		job->in_fence = NULL;
-		return fence;
-	}
 
 	/* XXX: Wait on a fence for switching the GMP if necessary,
 	 * and then do so.
 	 */
 
-	return NULL;
-}
+	if (!xa_empty(&job->deps))
+		return xa_erase(&job->deps, job->last_dep++);
 
-/**
- * Returns the fences that the render job depends on, one by one.
- * v3d_job_run() won't be called until all of them have been signaled.
- */
-static struct dma_fence *
-v3d_render_job_dependency(struct drm_sched_job *sched_job,
-			  struct drm_sched_entity *s_entity)
-{
-	struct v3d_render_job *job = to_render_job(sched_job);
-	struct dma_fence *fence;
-
-	fence = v3d_job_dependency(sched_job, s_entity);
-	if (fence)
-		return fence;
-
-	/* If we had a bin job, the render job definitely depends on
-	 * it. We first have to wait for bin to be scheduled, so that
-	 * its done_fence is created.
-	 */
-	fence = job->bin_done_fence;
-	if (fence) {
-		job->bin_done_fence = NULL;
-		return fence;
-	}
-
-	return fence;
+	return NULL;
 }
 
 static struct dma_fence *v3d_bin_job_run(struct drm_sched_job *sched_job)
@@ -394,7 +362,7 @@ static const struct drm_sched_backend_ops v3d_bin_sched_ops = {
 };
 
 static const struct drm_sched_backend_ops v3d_render_sched_ops = {
-	.dependency = v3d_render_job_dependency,
+	.dependency = v3d_job_dependency,
 	.run_job = v3d_render_job_run,
 	.timedout_job = v3d_render_job_timedout,
 	.free_job = v3d_job_free,