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author | Simon Ser <contact@emersion.fr> | 2021-01-15 12:06:26 +0100 |
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committer | Simon Ser <contact@emersion.fr> | 2021-01-24 10:37:50 +0100 |
commit | 97ecfff41e269d9c3114db85225bf1e493470a8f (patch) | |
tree | 0b6b75eeb3881b769da9a29733bea6e209f82ead /drivers/gpu/drm/drm_plane.c | |
parent | 7e5d1e122dff5d83069f9b77afa2618f32f115ba (diff) | |
download | linux-97ecfff41e269d9c3114db85225bf1e493470a8f.tar.gz linux-97ecfff41e269d9c3114db85225bf1e493470a8f.tar.bz2 linux-97ecfff41e269d9c3114db85225bf1e493470a8f.zip |
drm/doc: document the type plane property
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>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115110626.12233-2-contact@emersion.fr
Diffstat (limited to 'drivers/gpu/drm/drm_plane.c')
-rw-r--r-- | drivers/gpu/drm/drm_plane.c | 58 |
1 files changed, 54 insertions, 4 deletions
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index bf6e525bb116..8ec56cf4c1b6 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. + * + * Some 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. + * + * Some 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 |