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Date:   Tue, 6 Sep 2022 15:55:44 -0400
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Subject: Re: [PATCH v2 1/4] drm/sched: Enable signaling for finished fence
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To:     =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Arvind Yadav <Arvind.Yadav@amd.com>, shashank.sharma@amd.com,
        amaranath.somalapuram@amd.com, Arunpravin.PaneerSelvam@amd.com,
        sumit.semwal@linaro.org, gustavo@padovan.org, airlied@linux.ie,
        daniel@ffwll.ch, linux-media@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
        linux-kernel@vger.kernel.org
References: <20220905163502.4032-1-Arvind.Yadav@amd.com>
 <20220905163502.4032-2-Arvind.Yadav@amd.com>
 <5568fad0-1503-a0f3-222e-c238fd4eefdd@amd.com>
From:   Andrey Grodzovsky <andrey.grodzovsky@amd.com>
In-Reply-To: <5568fad0-1503-a0f3-222e-c238fd4eefdd@amd.com>
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On 2022-09-06 02:34, Christian König wrote:
> Am 05.09.22 um 18:34 schrieb Arvind Yadav:
>> Here's enabling software signaling for finished fence.
>>
>> Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
>> ---
>>
>> Changes in v1 :
>> 1- Addressing Christian's comment to remove CONFIG_DEBUG_FS check from
>> this patch.
>> 2- The version of this patch is also changed and previously
>> it was [PATCH 2/4]
>>
>> ---
>>   drivers/gpu/drm/scheduler/sched_main.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c 
>> b/drivers/gpu/drm/scheduler/sched_main.c
>> index e0ab14e0fb6b..fe72de0e2911 100644
>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>> @@ -962,6 +962,8 @@ static int drm_sched_main(void *param)
>>               /* Drop for original kref_init of the fence */
>>               dma_fence_put(fence);
>>   + dma_fence_enable_sw_signaling(&s_fence->finished);
>
> Ok, this makes it a lot clearer. Previously I though that we have some 
> bug in dma_fence_add_callback().
>
> This is essentially the wrong place to call this, the finished fence 
> should be enabled by the caller and not here.
>
> There is also another problem in dma_fence_enable_sw_signaling(), it 
> returns early when the fence is already signaled:
>
>         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
>                 return;
>
> Please remove that one first.


Why we even need this explicit call if dma_fence_add_callback calls 
__dma_fence_enable_signaling anyway ?

Andrey


>
> Thanks,
> Christian.
>
>
>> +
>>               r = dma_fence_add_callback(fence, &sched_job->cb,
>>                              drm_sched_job_done_cb);
>>               if (r == -ENOENT)
>