[PATCH] drm/fourcc: Document open source user waiver

[Daniel Vetter]

It's a bit a FAQ, and we really can't claim to be the authoritative
source for allocating these numbers used in many standard extensions
if we tell closed source or vendor stacks in general to go away.

Iirc this was already clarified in some vulkan discussions, but I
can't find that anywhere anymore. At least not in a public link.

Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: David Airlie <airlied at gmail.com>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Alex Deucher <alexdeucher at gmail.com>
Cc: Daniel Stone <daniel at fooishbar.org>
Cc: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Cc: Jason Ekstrand <jason at jlekstrand.net>
Cc: Neil Trevett <ntrevett at nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 include/uapi/drm/drm_fourcc.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index bc056f2d537d..de703c6be969 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -88,6 +88,18 @@ extern "C" {
  *
  * The authoritative list of format modifier codes is found in
  * `include/uapi/drm/drm_fourcc.h`
+ *
+ * Open Source User Waiver
+ * -----------------------
+ *
+ * Because this is the authoritative source for pixel formats and modifiers
+ * referenced by GL, Vulkan extensions and other standards and hence used both
+ * by open source and closed source driver stacks, the usual requirement for an
+ * upstream in-kernel or open source userspace user does not apply.
+ *
+ * To ensure, as much as feasible, compatibility across stacks and avoid
+ * confusion with incompatible enumerations stakeholders for all relevant driver
+ * stacks should approve additions.
  */
 
 #define fourcc_code(a, b, c, d) ((__u32)(a) | ((__u32)(b) << 8) | \
-- 
2.37.2