[PATCH v5 1/1] drm/amdgpu: Enable scatter gather display support

[Alex Deucher]

On Mon, Apr 23, 2018 at 12:44 PM, Samuel Li <Samuel.Li at amd.com> wrote:
> Enables sg display if vram size <= THRESHOLD(256M); otherwise
> still use vram as display buffer.
> This patch fixed some potention issues introduced by change
> "allow framebuffer in GART memory as well" due to CZ/ST hardware
> limitation.
>
> v2: Change default setting to auto.
> v3: Move some logic from amdgpu_display_framebuffer_domains()
>     to pin function, suggested by Christian.
> v4: Split into several patches.
> v5: Drop module parameter for now.
>
> Signed-off-by: Samuel Li <Samuel.Li at amd.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

We can add the checks for preferred domains as a follow on patch.

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h        | 1 +
>  drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 9 +++++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 59df4b7..2d75009 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -138,6 +138,7 @@ extern int amdgpu_si_support;
>  extern int amdgpu_cik_support;
>  #endif
>
> +#define AMDGPU_SG_THRESHOLD                    (256*1024*1024)
>  #define AMDGPU_DEFAULT_GTT_SIZE_MB             3072ULL /* 3GB by default */
>  #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS         3000
>  #define AMDGPU_MAX_USEC_TIMEOUT                        100000  /* 100 ms */
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 1985c08..e62153a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -701,6 +701,15 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
>                         return -EINVAL;
>         }
>
> +       /* This assumes only APU display buffers are pinned with (VRAM|GTT).
> +        * See function amdgpu_display_supported_domains()
> +        */
> +       if (domain == (AMDGPU_GEM_DOMAIN_VRAM | AMDGPU_GEM_DOMAIN_GTT)) {
> +               domain = AMDGPU_GEM_DOMAIN_VRAM;
> +               if (adev->gmc.real_vram_size <= AMDGPU_SG_THRESHOLD)
> +                       domain = AMDGPU_GEM_DOMAIN_GTT;
> +       }
> +
>         if (bo->pin_count) {
>                 uint32_t mem_type = bo->tbo.mem.mem_type;
>
> --
> 2.7.4
>
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