Am 13.02.19 um 19:58 schrieb Andrey Grodzovsky:
When ring hang happens amdgpu_dm_commit_planes during flip is holding
the BO reserved and then stack waiting for fences to signal in
reservation_object_wait_timeout_rcu (which won't signal because there
was a hnag). Then when we try to shutdown display block during reset
recovery from drm_atomic_helper_suspend we also try to reserve the BO
from dm_plane_helper_cleanup_fb ending in deadlock.
Also remove useless WARN_ON
Well it is good that you pointed this out, but there are more problems
than just waiting wile the BO is reserved here.
Signed-off-by: Andrey Grodzovsky <andrey.grodzov...@amd.com>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index acc4ff8..f8dec36 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4802,14 +4802,21 @@ static void amdgpu_dm_commit_planes(struct
drm_atomic_state *state,
*/
abo = gem_to_amdgpu_bo(fb->obj[0]);
r = amdgpu_bo_reserve(abo, true);
Well why do we reserve the BO in the first place? As the name indicates
reservation_object_wait_timeout_rcu() just uses rcu to wait for the BO
to be idle, no need to actually reserve it at all.
- if (unlikely(r != 0)) {
+ if (unlikely(r != 0))
DRM_ERROR("failed to reserve buffer before
flip\n");
- WARN_ON(1);
- }
- /* Wait for all fences on this FB */
-
WARN_ON(reservation_object_wait_timeout_rcu(abo->tbo.resv, true, false,
-
MAX_SCHEDULE_TIMEOUT) < 0);
+ /*
+ * Wait for all fences on this FB. Do limited wait to
avoid
+ * deadlock during GPU reset when this fence will not
signal
+ * but we hold reservation lock for the BO.
+ */
+ r = reservation_object_wait_timeout_rcu(abo->tbo.resv,
+ true, false,
Does this waiting happen in a work item or process context? If it's
process context we should actually try to wait interruptible here.
Regards,
Christian.
+
msecs_to_jiffies(5000));
+ if (unlikely(r == 0))
+ DRM_ERROR("Waiting for fences timed out.");
+
+
amdgpu_bo_get_tiling_flags(abo, &tiling_flags);
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