[PATCH] drm/amdgpu: Set GTT_USWC flag to enable freesync v2

[Christian König]

Hi Shashank,

can you give this patch a test round? In theory it should work, but I'm 
not 100% sure.

Thanks,
Christian.

Am 15.02.21 um 12:43 schrieb Christian König:
> From: Shashank Sharma <shashank.sharma at amd.com>
>
> This patch sets 'AMDGPU_GEM_CREATE_CPU_GTT_USWC' as input
> parameter flag, during object creation of an imported DMA
> buffer.
>
> In absence of this flag:
> 1. Function amdgpu_display_supported_domains() doesn't add
>     AMDGPU_GEM_DOMAIN_GTT as supported domain.
> 2. Due to which, Function amdgpu_display_user_framebuffer_create()
>     refuses to create framebuffer for imported DMA buffers.
> 3. Due to which, AddFB() IOCTL fails.
> 4. Due to which, amdgpu_present_check_flip() check fails in DDX
> 5. Due to which DDX driver doesn't allow flips (goes to blitting)
> 6. Due to which setting Freesync/VRR property fails for PRIME buffers.
>
> So, this patch finally enables Freesync with PRIME buffer offloading.
>
> v2 (chk): instead of just checking the flag we copy it over if the
>            exporter is an amdgpu device as well.
>
> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> index d3727f3ab277..a54a870f006c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> @@ -422,14 +422,22 @@ amdgpu_dma_buf_create_obj(struct drm_device *dev, struct dma_buf *dma_buf)
>   {
>   	struct dma_resv *resv = dma_buf->resv;
>   	struct amdgpu_device *adev = drm_to_adev(dev);
> -	struct amdgpu_bo *bo;
>   	struct drm_gem_object *gobj;
> +	struct amdgpu_bo *bo;
> +	uint64_t flags = 0;
>   	int ret;
>   
>   	dma_resv_lock(resv, NULL);
> +
> +	if (dma_buf->ops == &amdgpu_dmabuf_ops) {
> +		struct amdgpu_bo *other = gem_to_amdgpu_bo(dma_buf->priv);
> +
> +		flags |= other->flags & AMDGPU_GEM_CREATE_CPU_GTT_USWC;
> +	}
> +
>   	ret = amdgpu_gem_object_create(adev, dma_buf->size, PAGE_SIZE,
> -			AMDGPU_GEM_DOMAIN_CPU,
> -			0, ttm_bo_type_sg, resv, &gobj);
> +				       AMDGPU_GEM_DOMAIN_CPU, flags,
> +				       ttm_bo_type_sg, resv, &gobj);
>   	if (ret)
>   		goto error;
>