drm/scheduler: Change scheduled fence track v2

Update the timestamp of scheduled fence on HW
completion of the previous fences

This allow more accurate tracking of the fence
execution in HW

v2 (chk): drop the flag check and improve the comment

Signed-off-by: David M Nieto <david.nieto@amd.com>
Signed-off-by: Roy Sun <Roy.Sun@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210426062701.39732-1-Roy.Sun@amd.com

Author: Roy Sun

drivers/gpu/drm/scheduler/sched_main.c

@@ -671,7 +671,7 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
 static struct drm_sched_job *
 drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
 {
-	struct drm_sched_job *job;
+	struct drm_sched_job *job, *next;
 
 	/*
 	 * Don't destroy jobs while the timeout worker is running  OR thread
@@ -690,6 +690,13 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
 	if (job && dma_fence_is_signaled(&job->s_fence->finished)) {
 		/* remove job from pending_list */
 		list_del_init(&job->list);
+		/* make the scheduled timestamp more accurate */
+		next = list_first_entry_or_null(&sched->pending_list,
+						typeof(*next), list);
+		if (next)
+			next->s_fence->scheduled.timestamp =
+				job->s_fence->finished.timestamp;
+
 	} else {
 		job = NULL;
 		/* queue timeout for next job */