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

[Alex Deucher <alexdeucher@gmail.com>]

On Mon, Mar 20, 2023 at 8:30 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
>>
>>  #define AMDGPU_INFO_MMR_SE_INDEX_SHIFT 0
>>  #define AMDGPU_INFO_MMR_SE_INDEX_MASK  0xff
>> @@ -1203,6 +1204,15 @@ struct drm_amdgpu_info_video_caps {
>>         struct drm_amdgpu_info_video_codec_info codec_info[AMDGPU_INFO_VIDEO_CAPS_CODEC_IDX_COUNT];
>>  };
>>
>> +struct drm_amdgpu_info_cp_gfx_shadow_size {
>> +       __u32 shadow_size;
>> +       __u32 shadow_alignment;
>> +       __u32 csa_size;
>> +       __u32 csa_alignment;
>> +       __u32 gds_size;
>> +       __u32 gds_alignment;
>
>
> Can you document the fields? What is CSA? Also, why is GDS there when the hw deprecated it and replaced it with GDS registers?

Will add documentation.  For reference:
CSA (Context Save Area) - used as a scratch area for FW for saving
various things
Shadow - stores the pipeline state
GDS backup - stores the GDS state used by the pipeline.  I'm not sure
if this is registers or the old GDS memory.  Presumably the former.

Alex

>
> Thanks,
> Marek