[PATCH] drm/fourcc: Add Apple Interchange layout format modifier

[James Calligeros <jcalligeros99@gmail.com>]

Apple Interchange is a tiled and compressed image layout used
for buffer exchange between Apple hardware blocks. It is
similar to the already-supported GPU_TILED_COMPRESSED layout.

Add a format modifier for Apple Interchange so that it can be
used for buffer exchange.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
---
 include/uapi/drm/drm_fourcc.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index a103fdc0b3a3..aa51c116cd7d 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -1626,6 +1626,26 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
 #define DRM_FORMAT_MOD_APPLE_GPU_TILED fourcc_mod_code(APPLE, 1)
 #define DRM_FORMAT_MOD_APPLE_GPU_TILED_COMPRESSED fourcc_mod_code(APPLE, 2)
 
+/*
+ * Apple Interchange layout
+ *
+ * Apple Interchange is a compressed framebuffer format used exclusively for
+ * sharing buffers between hardware blocks (GPU, display controller, video
+ * codecs) on Apple platforms. It is similar to and uses the same compression
+ * scheme as GPU_TILED_COMPRESSED. There is no known uncompressed variant
+ * of Apple Interchange.
+ *
+ * Unlinke the GPU layouts, tile size is not dependent on bit depth. RGB
+ * images and the chroma components of YUV images use 16x16 tiles. The
+ * luma component of YUV images uses 32x32 tiles. Compression tiles
+ * are once again 16x16 with 8 bytes of metadata per compression subtile.
+ *
+ * AGX has limited support for Apple Interchange. It cannot be used for Z/S
+ * buffers or array images, for example. It is intended for scanout buffer
+ * sharing only.
+ */
+#define DRM_FORMAT_MOD_APPLE_INTERCHANGE fourcc_mod_code(APPLE, 3)
+
 /*
  * AMD modifiers
  *

---
base-commit: 08dbfad3f5040f5bdb6c529da20d6d4e81fefd72
change-id: 20260830-apple-interchange-modifier-cbcc311c835d

Best regards,
--  
James Calligeros <jcalligeros99@gmail.com>