[PATCH 3/3] drm: document minimum kernel version for DRM_CLIENT_CAP_*

[Simon Ser]

The kernel versions including the following commits are referenced:

DRM_CLIENT_CAP_STEREO_3D
61d8e3282541 ("drm: Add a STEREO_3D capability to the SET_CLIENT_CAP ioctl")

DRM_CLIENT_CAP_UNIVERSAL_PLANES
681e7ec73044 ("drm: Allow userspace to ask for universal plane list (v2)")
c7dbc6c9ae5c ("drm: Remove command line guard for universal planes")

DRM_CLIENT_CAP_ATOMIC
88a48e297b3a ("drm: add atomic properties")
8b72ce158cf0 ("drm: Always enable atomic API")

DRM_CLIENT_CAP_ASPECT_RATIO
7595bda2fb43 ("drm: Add DRM client cap for aspect-ratio")

DRM_CLIENT_CAP_WRITEBACK_CONNECTORS
d67b6a206507 ("drm: writeback: Add client capability for exposing writeback connectors")

Signed-off-by: Simon Ser <contact at emersion.fr>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Daniel Stone <daniels at collabora.com>
Cc: Pekka Paalanen <ppaalanen at gmail.com>
---
 include/uapi/drm/drm.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 87878aea4526..ec2b122cdcc5 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -780,6 +780,8 @@ struct drm_get_cap {
  * If set to 1, the DRM core will expose the stereo 3D capabilities of the
  * monitor by advertising the supported 3D layouts in the flags of struct
  * drm_mode_modeinfo. See ``DRM_MODE_FLAG_3D_*``.
+ *
+ * This capability is always supported starting from kernel version 3.13.
  */
 #define DRM_CLIENT_CAP_STEREO_3D	1
 
@@ -788,6 +790,9 @@ struct drm_get_cap {
  *
  * If set to 1, the DRM core will expose all planes (overlay, primary, and
  * cursor) to userspace.
+ *
+ * This capability has been introduced in kernel version 3.15. Starting from
+ * kernel version 3.17, this capability is always supported.
  */
 #define DRM_CLIENT_CAP_UNIVERSAL_PLANES  2
 
@@ -797,6 +802,13 @@ struct drm_get_cap {
  * If set to 1, the DRM core will expose atomic properties to userspace. This
  * implicitly enables &DRM_CLIENT_CAP_UNIVERSAL_PLANES and
  * &DRM_CLIENT_CAP_ASPECT_RATIO.
+ *
+ * If the driver doesn't support atomic mode-setting, enabling this capability
+ * will fail with -EOPNOTSUPP.
+ *
+ * This capability has been introduced in kernel version 4.0. Starting from
+ * kernel version 4.2, this capability is always supported for atomic-capable
+ * drivers.
  */
 #define DRM_CLIENT_CAP_ATOMIC	3
 
@@ -805,6 +817,8 @@ struct drm_get_cap {
  *
  * If set to 1, the DRM core will provide aspect ratio information in modes.
  * See ``DRM_MODE_FLAG_PIC_AR_*``.
+ *
+ * This capability is always supported starting from kernel version 4.18.
  */
 #define DRM_CLIENT_CAP_ASPECT_RATIO    4
 
@@ -814,6 +828,9 @@ struct drm_get_cap {
  * If set to 1, the DRM core will expose special connectors to be used for
  * writing back to memory the scene setup in the commit. The client must enable
  * &DRM_CLIENT_CAP_ATOMIC first.
+ *
+ * This capability is always supported for atomic-capable drivers starting from
+ * kernel version 4.19.
  */
 #define DRM_CLIENT_CAP_WRITEBACK_CONNECTORS	5
 
-- 
2.31.1