linux-kernel - Re: [PATCH v3 4/6] drm/amdgpu: Enable signaling on fence.

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Date:   Mon, 12 Sep 2022 10:46:47 +0200
From:   Christian König <christian.koenig@....com>
To:     Arvind Yadav <Arvind.Yadav@....com>, andrey.grodzovsky@....com,
        shashank.sharma@....com, amaranath.somalapuram@....com,
        Arunpravin.PaneerSelvam@....com, sumit.semwal@...aro.org,
        gustavo@...ovan.org, airlied@...ux.ie, daniel@...ll.ch,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/6] drm/amdgpu: Enable signaling on fence.

Am 09.09.22 um 19:08 schrieb Arvind Yadav:
> Here's enabling software signaling on fence because
> amdgpu_ctx_add_fence() is checking the status of fence
> and emits warning.
>
> Signed-off-by: Arvind Yadav <Arvind.Yadav@....com>
> ---
>
> Changes in v1, v2: This new patch was not part of previous series.
>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index afe22f83d4a6..21221d705588 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -730,6 +730,8 @@ uint64_t amdgpu_ctx_add_fence(struct amdgpu_ctx *ctx,
>   
>   	dma_fence_get(fence);
>   
> +	dma_fence_enable_sw_signaling(fence);
> +

That looks like a step into the right direction, but still isn't correct.

The code using this interface should call amdgpu_ctx_wait_prev_fence() 
before calling amdgpu_ctx_add_fence(). And amdgpu_ctx_wait_prev_fence() 
in turn calls dma_fence_wait() which should also enables the signaling.

So when we need this here something is still very wrong on the logic :)

Thanks,
Christian.

>   	spin_lock(&ctx->ring_lock);
>   	centity->fences[idx] = fence;
>   	centity->sequence++;