Hej,
On Tue, Feb 18, 2025 at 11:15:54AM -0500, Alyssa Rosenzweig wrote:
> Apple supports a few image layouts across the SoC. To begin, add
> modifiers for the "twiddled" and "twiddled + compressed" layouts. These
> are the two "standard" layouts used on the GPU. Mesa requires these
> modifiers to share non-linear buffers across processes, but no other
> userspace or kernel support is required/expected.
>
> These layouts are notably not used for interchange across hardware
> blocks (e.g. with the display controller). There are other layouts for
> those but we don't support them either in userspace or kernelspace yet
> (even downstream), so we're not adding them here.
>
> Signed-off-by: Alyssa Rosenzweig <aly...@rosenzweig.io>
> ---
> include/uapi/drm/drm_fourcc.h | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index
> e41a3cec6a9ed18760f3b0c88ba437c9aba3dd4f..6c289fc172c099ab32bf539a1698dabb93f9a0d2
> 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -422,6 +422,7 @@ extern "C" {
> #define DRM_FORMAT_MOD_VENDOR_ALLWINNER 0x09
> #define DRM_FORMAT_MOD_VENDOR_AMLOGIC 0x0a
> #define DRM_FORMAT_MOD_VENDOR_MTK 0x0b
> +#define DRM_FORMAT_MOD_VENDOR_APPLE 0x0c
>
> /* add more to the end as needed */
>
> @@ -1494,6 +1495,36 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64
> modifier)
> /* alias for the most common tiling format */
> #define DRM_FORMAT_MOD_MTK_16L_32S_TILE
> DRM_FORMAT_MOD_MTK(MTK_FMT_MOD_TILE_16L32S)
>
> +/*
> + * Apple twiddled layout.
> + *
> + * This is the most "general" image layout supported on Apple GPUs.
> + *
> + * Twiddled images are divided into tiles. Tiles are always 16KiB, with
> + * dimensions depending on the base-format. Within a tile, pixels are fully
> + * interleaved (Morton order). Tiles themselves are raster-order.
> + *
> + * Images must be 16-byte aligned.
> + *
> + * For more information see
> + * https://docs.mesa3d.org/drivers/asahi.html#image-layouts
> + */
> +#define DRM_FORMAT_MOD_APPLE_TWIDDLED fourcc_mod_code(APPLE, 1)
> +
> +/*
> + * Apple twiddled and compressed layout.
> + *
> + * This is the main lossless image compression layout supported by Apple
> GPUs.
> + *
> + * The image is divided into tiles that are internally twiddled. In
> addition to
Does the compressed format uses the same the sime tile sizes (in pixel
dimensions) and layout as DRM_FORMAT_MOD_APPLE_TWIDDLED? I'd assume so
but I think it's worth stating explictly.
> + * the body, there is also a metadata section containing 8 bytes for each
> 16x16
> + * compression subtile. By convention, the metadata immediately follows the
> + * body, after padding to 128-bytes.
> + *
> + * Images must be 16-byte aligned.
> + */
> +#define DRM_FORMAT_MOD_APPLE_TWIDDLED_COMPRESSED fourcc_mod_code(APPLE, 2)
> +
ciao Janne
