Unverified Commit 9999587b authored by Simon Ser's avatar Simon Ser
Browse files

drm: rework description of primary and cursor planes 

The previous wording could be understood by user-space evelopers as "a
primary/cursor plane is only compatible with a single CRTC" [1].

Reword the planes description to make it clear the DRM-internal
drm_crtc.primary and drm_crtc.cursor planes are for legacy uAPI.

[1]: https://github.com/swaywm/wlroots/pull/2333#discussion_r456788057



Signed-off-by: default avatarSimon Ser <contact@emersion.fr>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: default avatarPekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201211184634.74534-1-contact@emersion.fr
parent 010dbfbe

drivers/gpu/drm/drm_crtc.c

+3 −0
Original line number Diff line number Diff line
@@ -256,6 +256,9 @@ struct dma_fence *drm_crtc_create_fence(struct drm_crtc *crtc) 
 * planes). For really simple hardware which has only 1 plane look at

 * drm_simple_display_pipe_init() instead.

 *

 * The @primary and @cursor planes are only relevant for legacy uAPI, see

 * &drm_crtc.primary and &drm_crtc.cursor.

 *

 * Returns:

 * Zero on success, error code on failure.

 */

drivers/gpu/drm/drm_plane.c

+9 −7
Original line number Diff line number Diff line
@@ -49,14 +49,16 @@ 
 * &struct drm_plane (possibly as part of a larger structure) and registers it

 * with a call to drm_universal_plane_init().

 *

 * Cursor and overlay planes are optional. All drivers should provide one

 * primary plane per CRTC to avoid surprising userspace too much. See enum

 * drm_plane_type for a more in-depth discussion of these special uapi-relevant

 * plane types. Special planes are associated with their CRTC by calling

 * drm_crtc_init_with_planes().

 *

 * The type of a plane is exposed in the immutable "type" enumeration property,

 * which has one of the following values: "Overlay", "Primary", "Cursor".

 * which has one of the following values: "Overlay", "Primary", "Cursor" (see

 * enum drm_plane_type). A plane can be compatible with multiple CRTCs, see

 * &drm_plane.possible_crtcs.

 *

 * Legacy uAPI doesn't expose the primary and cursor planes directly. DRM core

 * relies on the driver to set the primary and optionally the cursor plane used

 * for legacy IOCTLs. This is done by calling drm_crtc_init_with_planes(). All

 * drivers should provide one primary plane per CRTC to avoid surprising legacy

 * userspace too much.

 */



static unsigned int drm_num_planes(struct drm_device *dev)