On Fri, 15 Jan 2021 12:06:26 +0100 Simon Ser <contact@xxxxxxxxxxx> wrote: > 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@xxxxxxxxxxx> > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > Cc: Pekka Paalanen <ppaalanen@xxxxxxxxx> > --- > 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. Hi, this part is kernel dev doc, right? > * > * 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 + * the plane type is just a hint and is mostly superseded by atomic 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 s/Primary planes/Some primary planes/ perhaps? That would give the justification for the below "user-space must not" sentence as there is vagueness in what exactly happens with legacy. Ok either way. > + * 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 s/Cursor planes/Some cursor planes/ like earlier? > + * 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. This is a bit terse. Can we say anything more about overlay planes? Even just "nothing is guaranteed, use test_only commits to find out what works"? > + * > * IN_FORMATS: > * Blob property which contains the set of buffer format and modifier > * pairs supported by this plane. The blob is a struct In any case, Reviewed-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx> Thanks, pq
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