[Intel-gfx] [PATCH 4/7] drm/i915/adlp/fb: Fix remapping of linear CCS AUX surfaces

[Matthew Auld]

On Tue, 26 Oct 2021 at 23:51, Imre Deak <imre.deak at intel.com> wrote:
>
> During remapping CCS FBs the CCS AUX surface mapped size and offset->x,y
> coordinate calculations assumed a tiled layout. This works as long as
> the CCS surface height is aligned to 64 lines (ensuring a 4k bytes CCS
> surface tile layout).  However this alignment is not required by the HW
> (and the driver doesn't enforces it either).
>
> Add the remapping logic required to remap the pages of CCS surfaces
> without the above alignment, assuming the natural linear layout of the
> CCS surface (vs. tiled main surface layout).
>
> Cc: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Fixes: 3d1adc3d64cf ("drm/i915/adlp: Add support for remapping CCS FBs")
> Signed-off-by: Imre Deak <imre.deak at intel.com>

<snip>

> diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
> index 80e93bf00f2e5..4ee6e54799f48 100644
> --- a/drivers/gpu/drm/i915/i915_vma_types.h
> +++ b/drivers/gpu/drm/i915/i915_vma_types.h
> @@ -97,11 +97,20 @@ enum i915_cache_level;
>
>  struct intel_remapped_plane_info {
>         /* in gtt pages */
> -       u32 offset;
> -       u16 width;
> -       u16 height;
> -       u16 src_stride;
> -       u16 dst_stride;
> +       u32 offset:31;
> +       u32 linear:1;
> +       union {
> +               /* in gtt pages for !linear */
> +               struct {
> +                       u16 width;
> +                       u16 height;
> +                       u16 src_stride;
> +                       u16 dst_stride;
> +               };
> +
> +               /* in gtt pages for linear */
> +               u32 size;
> +       };

Looks OK to me. Only concern is whether packed bitfields might give
different results, depending on the compiler or something. If you look
at the craziness in assert_i915_gem_gtt_types for example, it's very
particular about the size/layout.

>  } __packed;
>
>  struct intel_remapped_info {
> --
> 2.27.0
>