[PATCH v4 2/4] drm/amdgpu: Create helper to clear AMDGPU_GEM_CREATE_CPU_GTT_USWC

[Michel Dänzer]

On 2019-07-24 5:27 p.m., Andrey Grodzovsky wrote:
> Move the logic to clear AMDGPU_GEM_CREATE_CPU_GTT_USWC in
> amdgpu_bo_do_create into standalone helper so it can be reused
> in other functions.
> 
> v4:
> Switch to return bool.
> 
> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 61 +++++++++++++++++-------------
>  drivers/gpu/drm/amd/amdgpu/amdgpu_object.h |  2 +
>  2 files changed, 37 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 989b7b5..dafdb68 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -413,6 +413,40 @@ static bool amdgpu_bo_validate_size(struct amdgpu_device *adev,
>  	return false;
>  }
>  
> +bool amdgpu_bo_support_uswc(u64 bo_flags)
> +{
> +
> +#ifdef CONFIG_X86_32
> +	/* XXX: Write-combined CPU mappings of GTT seem broken on 32-bit
> +	 * See https://bugs.freedesktop.org/show_bug.cgi?id=84627
> +	 */
> +	return false

Missing semicolon.


> +#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT)
> +	/* Don't try to enable write-combining when it can't work, or things
> +	 * may be slow
> +	 * See https://bugs.freedesktop.org/show_bug.cgi?id=88758
> +	 */
> +
> +#ifndef CONFIG_COMPILE_TEST
> +#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better performance \
> +	 thanks to write-combining
> +#endif
> +
> +	if (bo_flags & AMDGPU_GEM_CREATE_CPU_GTT_USWC)
> +		DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for "
> +			      "better performance thanks to write-combining\n");

The AMDGPU_GEM_CREATE_CPU_GTT_USWC check will always pass at some point
due to patch 1, so passing in the flags is kind of pointless. Just do
the DRM_INFO_ONCE unconditionally here.


> @@ -466,33 +500,8 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev,
>  
> [...]
>  
> +	if (amdgpu_bo_support_uswc(bo->flags))
>  		bo->flags &= ~AMDGPU_GEM_CREATE_CPU_GTT_USWC;

Missing "!".


-- 
Earthling Michel Dänzer               |              https://www.amd.com
Libre software enthusiast             |             Mesa and X developer