Re: [PATCH 1/2] drm/sched: add DRM_SCHED_FENCE_DONT_PIPELINE flag

[Luben Tuikov <luben.tuikov@amd.com>]

On 2022-10-18 11:37, Alex Deucher wrote:
> On Tue, Oct 18, 2022 at 11:11 AM Christian König
> <christian.koenig@amd.com> wrote:
>>
>> Gentle ping to others to get this reviewed.
>>
>> Alex, this is fixing the TLB flush errors and I think we need to get it
>> into -fixes ASAP.
>>
>> Christian.
>>
>> Am 14.10.22 um 10:15 schrieb Christian König:
>>> Setting this flag on a scheduler fence prevents pipelining of jobs
>>> depending on this fence. In other words we always insert a full CPU
>>> round trip before dependen jobs are pushed to the pipeline.
> 
> typo: dependen -> dependent
> 
>>>
>>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>> CC: stable@vger.kernel.org # 5.19+
> 
> Please add a link to the bug as well for both patches.  With those
> fixed, series is:
> Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

Hi Christian,

Thanks for fixing this. You can add my,

Acked-by: Luben Tuikov <luben.tuikov@amd.com>

Regards,
Luben

> 
>>> ---
>>>   drivers/gpu/drm/scheduler/sched_entity.c | 3 ++-
>>>   include/drm/gpu_scheduler.h              | 9 +++++++++
>>>   2 files changed, 11 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
>>> index 191c56064f19..43d337d8b153 100644
>>> --- a/drivers/gpu/drm/scheduler/sched_entity.c
>>> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
>>> @@ -385,7 +385,8 @@ static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
>>>       }
>>>
>>>       s_fence = to_drm_sched_fence(fence);
>>> -     if (s_fence && s_fence->sched == sched) {
>>> +     if (s_fence && s_fence->sched == sched &&
>>> +         !test_bit(DRM_SCHED_FENCE_DONT_PIPELINE, &fence->flags)) {
>>>
>>>               /*
>>>                * Fence is from the same scheduler, only need to wait for
>>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>>> index 0fca8f38bee4..f01d14b231ed 100644
>>> --- a/include/drm/gpu_scheduler.h
>>> +++ b/include/drm/gpu_scheduler.h
>>> @@ -32,6 +32,15 @@
>>>
>>>   #define MAX_WAIT_SCHED_ENTITY_Q_EMPTY msecs_to_jiffies(1000)
>>>
>>> +/**
>>> + * DRM_SCHED_FENCE_DONT_PIPELINE - Prefent dependency pipelining
>>> + *
>>> + * Setting this flag on a scheduler fence prevents pipelining of jobs depending
>>> + * on this fence. In other words we always insert a full CPU round trip before
>>> + * dependen jobs are pushed to the hw queue.
>>> + */
>>> +#define DRM_SCHED_FENCE_DONT_PIPELINE        DMA_FENCE_FLAG_USER_BITS
>>> +
>>>   struct drm_gem_object;
>>>
>>>   struct drm_gpu_scheduler;
>>