Re: [PATCH 07/11] drm/amdgpu: add UAPI to query GFX shadow sizes

["Marek Olšák" <maraeo@gmail.com>]

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On Tue, Mar 21, 2023 at 3:54 PM Alex Deucher <alexdeucher@gmail.com> wrote:

> On Mon, Mar 20, 2023 at 8:31 PM Marek Olšák <maraeo@gmail.com> wrote:
> >
> > On Mon, Mar 20, 2023 at 1:38 PM Alex Deucher <alexander.deucher@amd.com>
> wrote:
> >>
> >> Add UAPI to query the GFX shadow buffer requirements
> >> for preemption on GFX11.  UMDs need to specify the shadow
> >> areas for preemption.
> >>
> >> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> >> ---
> >>  include/uapi/drm/amdgpu_drm.h | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >>
> >> diff --git a/include/uapi/drm/amdgpu_drm.h
> b/include/uapi/drm/amdgpu_drm.h
> >> index 3d9474af6566..19a806145371 100644
> >> --- a/include/uapi/drm/amdgpu_drm.h
> >> +++ b/include/uapi/drm/amdgpu_drm.h
> >> @@ -886,6 +886,7 @@ struct drm_amdgpu_cs_chunk_cp_gfx_shadow {
> >>         #define AMDGPU_INFO_VIDEO_CAPS_DECODE           0
> >>         /* Subquery id: Encode */
> >>         #define AMDGPU_INFO_VIDEO_CAPS_ENCODE           1
> >> +#define AMDGPU_INFO_CP_GFX_SHADOW_SIZE         0x22
> >
> >
> > Can you put this into the device structure instead? Let's minimize the
> number of kernel queries as much as possible.
>
> I guess, but one nice thing about this is that we can use the query as
> a way to determine if the kernel supports this functionality or not.
> If not, the query returns -ENOTSUP.
>

That should be another flag in the device info structure or the sizes
should be 0. There is never a reason to add a new single-value INFO query.

Marek

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