[PATCH] drm/amdgpu: take runtime pm reference when we attach a buffer

[Shashank Sharma]

On 09/12/20 11:00 pm, Alex Deucher wrote:
> On Fri, Dec 4, 2020 at 3:41 PM Alex Deucher <alexdeucher at gmail.com> wrote:
>> And drop it when we detach.  If the shared buffer is in vram,
>> we need to make sure we don't put the device into runtime
>> suspend.
>>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>
> Ping?  Any thoughts on this?  We really only need this for p2p since
> device memory in involved, but I'm not sure of the best way to handle
> that.
>
> Alex
>
>
>> ---
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 16 ++++++++++++++--
>>  1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>> index 5b465ab774d1..f63f182f37f9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>> @@ -40,6 +40,7 @@
>>  #include <linux/dma-buf.h>
>>  #include <linux/dma-fence-array.h>
>>  #include <linux/pci-p2pdma.h>
>> +#include <linux/pm_runtime.h>
>>
>>  /**
>>   * amdgpu_gem_prime_vmap - &dma_buf_ops.vmap implementation
>> @@ -187,9 +188,13 @@ static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf,
>>         if (attach->dev->driver == adev->dev->driver)
>>                 return 0;
>>
>> +       r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
>> +       if (r < 0)
>> +               goto out;
>> +
I am a bit skeptical if we should fail the BO reserve if we don't get the sync ? I was hoping to continue with it, with a warning maybe, so that it doesn't block the existing functionality ?
>>         r = amdgpu_bo_reserve(bo, false);
>>         if (unlikely(r != 0))
>> -               return r;
>> +               goto out;
>>
>>         /*
>>          * We only create shared fences for internal use, but importers
>> @@ -201,11 +206,15 @@ static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf,
>>          */
>>         r = __dma_resv_make_exclusive(bo->tbo.base.resv);
>>         if (r)
>> -               return r;
>> +               goto out;
>>
>>         bo->prime_shared_count++;
>>         amdgpu_bo_unreserve(bo);
>>         return 0;
>> +
>> +out:
>> +       pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);

Why not just pm_runtime_put_sync ? Why autosuspend ?

- Shashank

>> +       return r;
>>  }
>>
>>  /**
>> @@ -225,6 +234,9 @@ static void amdgpu_dma_buf_detach(struct dma_buf *dmabuf,
>>
>>         if (attach->dev->driver != adev->dev->driver && bo->prime_shared_count)
>>                 bo->prime_shared_count--;
>> +
>> +       pm_runtime_mark_last_busy(adev_to_drm(adev)->dev);
>> +       pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
>>  }
>>
>>  /**
>> --
>> 2.25.4
>>
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