linux-kernel - Re: [PATCH v3 18/28] drm/amdgpu: move sched status check inside amdgpu_ttm_set_buffer_funcs

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Message-ID: <29299d67-d7e5-435e-9c80-89d8cce6ed95@amd.com>
Date: Fri, 21 Nov 2025 16:23:52 +0100
From: Christian König <christian.koenig@....com>
To: Pierre-Eric Pelloux-Prayer <pierre-eric@...sy.net>,
 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 v3 18/28] drm/amdgpu: move sched status check inside
 amdgpu_ttm_set_buffer_funcs_status



On 11/21/25 16:12, Pierre-Eric Pelloux-Prayer wrote:
> 
> 
> Le 21/11/2025 à 16:08, Christian König a écrit :
>>
>>
>> On 11/21/25 11:12, Pierre-Eric Pelloux-Prayer wrote:
>>> It avoids duplicated code and allows to output a warning.
>>>
>>> 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    |  6 ++++++
>>>   2 files changed, 10 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 489880b2fb8e..9024dde0c5a7 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> @@ -2233,6 +2233,12 @@ u32 amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
>>>           adev->mman.buffer_funcs_enabled == enable || adev->gmc.is_app_apu)
>>>           return reserved_windows;
>>>   +    if ((!adev->mman.buffer_funcs_ring || !adev->mman.buffer_funcs_ring->sched.ready) &&
>>> +        enable) {
>>> +        dev_warn(adev->dev, "Not enabling DMA transfers for in kernel use");
>>> +        return 0;
>>> +    }
>>> +
>>
>> Only check that when enabling the functions. Could be that when disabling them we have sched.ready set to false already.
> 
> The check already has a "&& enable" condition. Are you suggesting something different?

Ah, missed that. But you have an "if (enabled) {" right below it. So I suggest to just move the check in there.

Regards,
Christian.

> 
> PE
> 
> 
>>
>> Apart from that looks good to me.
>>
>> Regards,
>> Christian.
>>
>>>       if (enable) {
>>>           struct amdgpu_ring *ring;
>>>           struct drm_gpu_scheduler *sched;