[PATCH 4/4] drm/amd/display: Restore deleted patch to resolve reset deadlock.

[Grodzovsky, Andrey]

On 4/12/19 3:40 AM, Christian König wrote:
> Am 11.04.19 um 18:03 schrieb Andrey Grodzovsky:
>> Patch '5edb0c9b Fix deadlock with display during hanged ring recovery'
>> was accidentaly removed during one of DALs code merges.
>>
>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at 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 0648794..27e0383 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -5138,14 +5138,21 @@ 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);
>> -        if (unlikely(r != 0)) {
>> +        if (unlikely(r != 0))
>>               DRM_ERROR("failed to reserve buffer before flip\n");
>> -            WARN_ON(1);
>> -        }
>
> I also already suggested to completely stop waiting while the BO is 
> being reserved, but looks like that got dropped as well.
>
> I would say something is seriously wrong with DALs development process 
> here.
>
> Christian.


Yea, I think your patch that moved the wait out of the reserved section 
got dropped as well, when I re spin the series with your comments for 
the TDR stuff I will also add a patch restoring your change.

Andrey


>
>>   -        /* 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,
>> +                            msecs_to_jiffies(5000));
>> +        if (unlikely(r == 0))
>> +            DRM_ERROR("Waiting for fences timed out.");
>> +
>> +
>>             amdgpu_bo_get_tiling_flags(abo, &tiling_flags);
>