Add a new entry for "type" in the section for standard plane properties.
v3: improve paragraph about mixing legacy IOCTLs with explicit usage, note that a driver may support cursors without cursor planes (Daniel)
v4: fixing rebase gone wrong
v5: - Fix typo (Daniel) - Mention CAP_ATOMIC instead of CAP_UNIVERSAL_PLANES when referring to atomic test-only commits (Daniel) - Add newlines at end of sections (Daniel)
Signed-off-by: Simon Ser contact@emersion.fr Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com --- drivers/gpu/drm/drm_plane.c | 58 ++++++++++++++++++++++++++++++++++--- 1 file changed, 54 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index bf6e525bb116..5affcc7f065b 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -50,10 +50,8 @@ * &struct drm_plane (possibly as part of a larger structure) and registers it * with a call to drm_universal_plane_init(). * - * The type of a plane is exposed in the immutable "type" enumeration property, - * 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. + * Each plane has a type, see enum drm_plane_type. A plane can be compatible + * with multiple CRTCs, see &drm_plane.possible_crtcs. * * Each CRTC must have a unique primary plane userspace can attach to enable * the CRTC. In other words, userspace must be able to attach a different @@ -73,6 +71,58 @@ * * DRM planes have a few standardized properties: * + * type: + * Immutable property describing the type of the plane. + * + * For user-space which has enabled the &DRM_CLIENT_CAP_ATOMIC capability, + * the plane type is just a hint and is mostly superseded by atomic + * test-only commits. The type hint can still be used to come up more + * easily with a plane configuration accepted by the driver. + * + * The value of this property can be one of the following: + * + * "Primary": + * To light up a CRTC, attaching a primary plane is the most likely to + * work if it covers the whole CRTC and doesn't have scaling or + * cropping set up. + * + * Drivers may support more features for the primary plane, user-space + * can find out with test-only atomic commits. + * + * Primary planes are implicitly used by the kernel in the legacy + * IOCTLs &DRM_IOCTL_MODE_SETCRTC and &DRM_IOCTL_MODE_PAGE_FLIP. + * Therefore user-space must not mix explicit usage of any primary + * plane (e.g. through an atomic commit) with these legacy IOCTLs. + * + * "Cursor": + * To enable this plane, using a framebuffer configured without scaling + * or cropping and with the following properties is the most likely to + * work: + * + * - If the driver provides the capabilities &DRM_CAP_CURSOR_WIDTH and + * &DRM_CAP_CURSOR_HEIGHT, create the framebuffer with this size. + * Otherwise, create a framebuffer with the size 64x64. + * - If the driver doesn't support modifiers, create a framebuffer with + * a linear layout. Otherwise, use the IN_FORMATS plane property. + * + * Drivers may support more features for the cursor plane, user-space + * can find out with test-only atomic commits. + * + * Cursor planes are implicitly used by the kernel in the legacy + * IOCTLs &DRM_IOCTL_MODE_CURSOR and &DRM_IOCTL_MODE_CURSOR2. + * Therefore user-space must not mix explicit usage of any cursor + * plane (e.g. through an atomic commit) with these legacy IOCTLs. + * + * Some drivers may support cursors even if no cursor plane is exposed. + * In this case, the legacy cursor IOCTLs can be used to configure the + * cursor. + * + * "Overlay": + * Neither primary nor cursor. + * + * Overlay planes are the only planes exposed when the + * &DRM_CLIENT_CAP_UNIVERSAL_PLANES capability is disabled. + * * IN_FORMATS: * Blob property which contains the set of buffer format and modifier * pairs supported by this plane. The blob is a struct