The docs for enum drm_plane_type mention legacy IOCTLs, however the
plane type is not tied to legacy IOCTLs, the drm_cursor.primary and
cursor fields are. Add a small paragraph to reference these.
Instead, document expectations for primary and cursor planes for
non-legacy userspace. Note that these docs are for driver developers,
not userspace developers, so internal kernel APIs are mentionned.
Signed-off-by: Simon Ser <cont...@emersion.fr>
Reviewed-by: Daniel Vetter <dan...@ffwll.ch>
Cc: Pekka Paalanen <ppaala...@gmail.com>
---
include/drm/drm_plane.h | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index 8ef06ee1c8eb..95ab14a4336a 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -538,10 +538,14 @@ struct drm_plane_funcs {
*
* For compatibility with legacy userspace, only overlay planes are made
* available to userspace by default. Userspace clients may set the
- * DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that they
+ * &DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that they
* wish to receive a universal plane list containing all plane types. See also
* drm_for_each_legacy_plane().
*
+ * In addition to setting each plane's type, drivers need to setup the
+ * &drm_crtc.primary and optionally &drm_crtc.cursor pointers for legacy
+ * IOCTLs. See drm_crtc_init_with_planes().
+ *
* WARNING: The values of this enum is UABI since they're exposed in the "type"
* property.
*/
@@ -557,19 +561,20 @@ enum drm_plane_type {
/**
* @DRM_PLANE_TYPE_PRIMARY:
*
- * Primary planes represent a "main" plane for a CRTC. Primary planes
- * are the planes operated upon by CRTC modesetting and flipping
- * operations described in the &drm_crtc_funcs.page_flip and
- * &drm_crtc_funcs.set_config hooks.
+ * A primary plane attached to a CRTC is the most likely to be able to
+ * light up the CRTC when no scaling/cropping is used and the plane
+ * covers the whole CRTC.
*/
DRM_PLANE_TYPE_PRIMARY,
/**
* @DRM_PLANE_TYPE_CURSOR:
*
- * Cursor planes represent a "cursor" plane for a CRTC. Cursor planes
- * are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and
- * DRM_IOCTL_MODE_CURSOR2 IOCTLs.
+ * A cursor plane attached to a CRTC is more likely to be able to be
+ * enabled when no scaling/cropping is used and the framebuffer has the
+ * size indicated by &drm_mode_config.cursor_width and
+ * &drm_mode_config.cursor_height. Additionally, if the driver doesn't
+ * support modifiers, the framebuffer should have a linear layout.
*/
DRM_PLANE_TYPE_CURSOR,
};
--
2.30.0
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