Re: [PATCH v2] drm: add ARM interleaved 64k modifier

[Liviu Dudau <liviu.dudau@arm.com>]

On Tue, Jan 27, 2026 at 11:07:39AM +0000, Caterina Shablia wrote:
> This modifier is primarily intended to be used by panvk to implement
> sparse partially-resident images with better map and unmap
> performance, and no worse access performance, compared to
> implementing them in terms of U-interleaved.
> 
> With this modifier, the plane is divided into 64k byte 1:1 or 2:1
> -sided tiles. The 64k tiles are laid out linearly. Each 64k tile
> is divided into blocks of 16x16 texel blocks each, which themselves
> are laid out linearly within a 64k tile. Then within each such
> 16x16 block, texel blocks are laid out according to U order,
> similar to 16X16_BLOCK_U_INTERLEAVED.
> 
> Unlike 16X16_BLOCK_U_INTERLEAVED, the layout does not depend on
> whether a format is compressed or not.
> 
> The hardware features corresponding to this modifier are available
> starting with v10 (second gen Valhall.)
> 
> The corresponding panvk MR can be found at:
> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38986
> 
> Previous patch:
> https://lists.freedesktop.org/archives/dri-devel/2026-January/546655.html
> 
> Changes since v1:
> 
> * Rewrite the description of the modifier to be hopefully unambiguous.
> 
> Signed-off-by: Caterina Shablia <caterina.shablia@collabora.com>

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  include/uapi/drm/drm_fourcc.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index e527b24bd824..452f901513ad 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -1422,6 +1422,22 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
>  #define DRM_FORMAT_MOD_ARM_16X16_BLOCK_U_INTERLEAVED \
>  	DRM_FORMAT_MOD_ARM_CODE(DRM_FORMAT_MOD_ARM_TYPE_MISC, 1ULL)
>  
> +/*
> + * ARM 64k interleaved modifier
> + *
> + * This is used by ARM Mali v10+ GPUs. With this modifier, the plane is divided
> + * into 64k byte 1:1 or 2:1 -sided tiles. The 64k tiles are laid out linearly.
> + * Each 64k tile is divided into blocks of 16x16 texel blocks, which are
> + * themselves laid out linearly within a 64k tile. Then within each 16x16
> + * block, texel blocks are laid out according to U order, similar to
> + * 16X16_BLOCK_U_INTERLEAVED.
> + *
> + * Note that unlike 16X16_BLOCK_U_INTERLEAVED, the layout does not change
> + * depending on whether a format is compressed or not.
> + */
> +#define DRM_FORMAT_MOD_ARM_INTERLEAVED_64K \
> +	DRM_FORMAT_MOD_ARM_CODE(DRM_FORMAT_MOD_ARM_TYPE_MISC, 2ULL)
> +
>  /*
>   * Allwinner tiled modifier
>   *
> 
> base-commit: f08f665f8cda9520d98ee24545d306a92f386616
> -- 
> 2.47.3
>