linux-kernel - Re: [PATCH v4 13/13] drm/amdgpu: move sched status check inside amdgpu_ttm_set_buffer_funcs

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Message-ID: <c162195a-d783-4576-b8b6-19057f98bc63@amd.com>
Date: Tue, 2 Dec 2025 12:53:51 +0100
From: Christian König <christian.koenig@....com>
To: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@....com>,
 Alex Deucher <alexander.deucher@....com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 13/13] drm/amdgpu: move sched status check inside
 amdgpu_ttm_set_buffer_funcs_status



On 12/2/25 10:47, Pierre-Eric Pelloux-Prayer wrote:
> It avoids duplicated code and allows to output a warning.
> 
> ---
> v4: move check inside the existing if (enable) test
> ---
> 
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@....com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 13 ++++---------
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    |  5 +++++
>  2 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 54f7c81f287b..7167db54d722 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3309,9 +3309,7 @@ static int amdgpu_device_ip_init(struct amdgpu_device *adev)
>  	if (r)
>  		goto init_failed;
>  
> -	if (adev->mman.buffer_funcs_ring &&
> -	    adev->mman.buffer_funcs_ring->sched.ready)
> -		amdgpu_ttm_set_buffer_funcs_status(adev, true);
> +	amdgpu_ttm_set_buffer_funcs_status(adev, true);
>  
>  	/* Don't init kfd if whole hive need to be reset during init */
>  	if (adev->init_lvl->level != AMDGPU_INIT_LEVEL_MINIMAL_XGMI) {
> @@ -4191,8 +4189,7 @@ static int amdgpu_device_ip_resume(struct amdgpu_device *adev)
>  
>  	r = amdgpu_device_ip_resume_phase2(adev);
>  
> -	if (adev->mman.buffer_funcs_ring->sched.ready)
> -		amdgpu_ttm_set_buffer_funcs_status(adev, true);
> +	amdgpu_ttm_set_buffer_funcs_status(adev, true);
>  
>  	if (r)
>  		return r;
> @@ -5321,8 +5318,7 @@ int amdgpu_device_suspend(struct drm_device *dev, bool notify_clients)
>  	return 0;
>  
>  unwind_evict:
> -	if (adev->mman.buffer_funcs_ring->sched.ready)
> -		amdgpu_ttm_set_buffer_funcs_status(adev, true);
> +	amdgpu_ttm_set_buffer_funcs_status(adev, true);
>  	amdgpu_fence_driver_hw_init(adev);
>  
>  unwind_userq:
> @@ -6050,8 +6046,7 @@ int amdgpu_device_reinit_after_reset(struct amdgpu_reset_context *reset_context)
>  				if (r)
>  					goto out;
>  
> -				if (tmp_adev->mman.buffer_funcs_ring->sched.ready)
> -					amdgpu_ttm_set_buffer_funcs_status(tmp_adev, true);
> +				amdgpu_ttm_set_buffer_funcs_status(tmp_adev, true);
>  
>  				r = amdgpu_device_ip_resume_phase3(tmp_adev);
>  				if (r)
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index ad53789d0e2b..ef68c5f706d2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -2223,6 +2223,11 @@ u32 amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
>  		struct amdgpu_ring *ring;
>  		struct drm_gpu_scheduler *sched;
>  
> +		if (!adev->mman.buffer_funcs_ring || !adev->mman.buffer_funcs_ring->sched.ready) {
> +			dev_warn(adev->dev, "Not enabling DMA transfers for in kernel use");
> +			return 0;
> +		}
> +
>  		ring = adev->mman.buffer_funcs_ring;
>  		sched = &ring->sched;

The ring and sched are assigned to local variables here, so you could move that check just a few more lines down.

Apart from that looks good to me.

Regards,
Christian.

>  		r = drm_sched_entity_init(&adev->mman.default_entity.base,