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.

Reviewed-by: Alyssa Rosenzweig <[email protected]>
Signed-off-by: James Calligeros <[email protected]>
---
Changes in v3:
- Explicitly mention lack of stride and single-plane treatment
- Pick up Alyssa's R-b
- Link to v2: 
https://patch.msgid.link/[email protected]

Changes in v2:
- Fix typo
- Link to v1: 
https://patch.msgid.link/[email protected]

To: Maarten Lankhorst <[email protected]>
To: Maxime Ripard <[email protected]>
To: Thomas Zimmermann <[email protected]>
To: David Airlie <[email protected]>
To: Simona Vetter <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
 include/uapi/drm/drm_fourcc.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index a103fdc0b3a3..0bb049f91524 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -1626,6 +1626,30 @@ 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.
+ *
+ * Unlike 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.
+ *
+ * Following the example set by GPU_TILED_{,COMPRESSED}, Interchange images
+ * are treated as a single plane by software and do not have a meaningful
+ * stride.
+ *
+ * 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 <[email protected]>

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