Subject: Re: [PATCH] drm/amdgpu: replace readq/writeq with atomic64 operations

From: Jisheng Zhang <[email-masked]>
Date: Wed, 7 Aug 2019 03:09:05 +0000

On Wed, 7 Aug 2019 10:56:40 +0800 Tao Zhou wrote:

> 
> 
> readq/writeq are not supported on all architectures
> 
> Signed-off-by: Tao Zhou <[email-masked]>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 558fe6d091ed..7eb9e0b9235a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -272,14 +272,10 @@ void amdgpu_mm_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v,
>   */
>  uint64_t amdgpu_mm_rreg64(struct amdgpu_device *adev, uint32_t reg)
>  {
> -       uint64_t ret;
> -
>         if ((reg * 4) < adev->rmmio_size)
> -               ret = readq(((void __iomem *)adev->rmmio) + (reg * 4));
> +               return atomic64_read((atomic64_t *)(adev->rmmio + (reg * 4)));

atomic64_read doesn't equal to readq on some architectures..

>         else
>                 BUG();
> -
> -       return ret;
>  }
> 
>  /**
> @@ -294,7 +290,7 @@ uint64_t amdgpu_mm_rreg64(struct amdgpu_device *adev, uint32_t reg)
>  void amdgpu_mm_wreg64(struct amdgpu_device *adev, uint32_t reg, uint64_t v)
>  {
>         if ((reg * 4) < adev->rmmio_size)
> -               writeq(v, ((void __iomem *)adev->rmmio) + (reg * 4));
> +               atomic64_set((atomic64_t *)(adev->rmmio + (reg * 4)), v);
>         else
>                 BUG();
>  }
> --
> 2.17.1

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