On 9/9/2022 11:02 PM, Andrey Grodzovsky wrote:
What exactly is the scenario which this patch fixes in more detail
please ?
GPU reset issue started after adding [PATCH 6/6].
Root cause -> In drm_sched_get_cleanup_job(), We use the finished fence
status bit to check the job status dma_fence_is_signaled(). If a job is
signaled (DMA_FENCE_FLAG_SIGNALED_BIT is set), then we cancel the reset
worker thread.
After applying [patch 6] now we are checking enable signaling in
dma_fence_is_signaled() by checking DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT
bit. but signaling is not enabled for the finished fence. As a result,
dma_fence_is_signaled() always returns false, and
drm_sched_get_cleanup_job() will not cancel the reset worker thread,
resulting in the GPU reset.
To Fix the above issue Christian suggested that we can use
parent(hardware) fence instead of finished fence because signaling
enabled by the calling of dma_fence_add_callback() for parent fence. As
a result, dma_fence_is_signaled() will return the correct fence status
and reset worker thread can be cancelled in drm_sched_get_cleanup_job().
~arvind
Andrey
On 2022-09-09 13:08, Arvind Yadav wrote:
Using the parent fence instead of the finished fence
to get the job status. This change is to avoid GPU
scheduler timeout error which can cause GPU reset.
Signed-off-by: Arvind Yadav <Arvind.Yadav@xxxxxxx>
---
changes in v1,v2 - Enable signaling for finished fence in sche_main()
is removed
---
drivers/gpu/drm/scheduler/sched_main.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_main.c
b/drivers/gpu/drm/scheduler/sched_main.c
index e0ab14e0fb6b..2ac28ad11432 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -829,7 +829,7 @@ drm_sched_get_cleanup_job(struct
drm_gpu_scheduler *sched)
job = list_first_entry_or_null(&sched->pending_list,
struct drm_sched_job, list);
- if (job && dma_fence_is_signaled(&job->s_fence->finished)) {
+ if (job && dma_fence_is_signaled(job->s_fence->parent)) {
/* remove job from pending_list */
list_del_init(&job->list);
@@ -841,7 +841,7 @@ drm_sched_get_cleanup_job(struct
drm_gpu_scheduler *sched)
if (next) {
next->s_fence->scheduled.timestamp =
- job->s_fence->finished.timestamp;
+ job->s_fence->parent->timestamp;
/* start TO timer for next job */
drm_sched_start_timeout(sched);
}
