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: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201211184634.74534-1-contact@emersion.fr
This commit is contained in:
Simon Ser 2020-12-11 19:46:31 +01:00
parent 010dbfbe7b
commit 9999587b68
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2 changed files with 12 additions and 7 deletions

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@ -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.
*/

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@ -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)