On Thu, Aug 06, 2020 at 10:33:31AM +0000, Simon Ser wrote: > Some drivers may expose primary planes compatible with multiple CRTCs. > Make this clear in the docs: the current wording may be misunderstood as > "exactly one primary plane per CRTC". > > Signed-off-by: Simon Ser <contact@xxxxxxxxxxx> > Cc: Daniel Vetter <daniel@xxxxxxxx> > --- > drivers/gpu/drm/drm_plane.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c > index b7b90b3a2e38..108a922e8c23 100644 > --- a/drivers/gpu/drm/drm_plane.c > +++ b/drivers/gpu/drm/drm_plane.c > @@ -49,8 +49,8 @@ > * &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 > + * Cursor and overlay planes are optional. All drivers should provide at least > + * one primary plane per CRTC to avoid surprising userspace too much. See enum I think that's even more confusing, since this reads like there could be multiple primary planes for a specific CRTC. That's not the case, there' only one pointer going from drm_crtc->primary to a drm_plane in the kernel. The problem is that userspace doesn't have a drm_property to read this pointer, and needs to guess. I thought the rule is: Nth primary plane (or cursor) is the primary plane for the Nth crtc. Enumaration with increasing drm kms object ids. And I guess we should explain that on some hw any plane (including primary ones, since that's only a sw construct) can be freely assinged to crtc. Yes it's probably the most gloriously bonkers uapi we've come up with. Might be so bad that a libdrm helper to look up the primary plane for a crtc (or it's cursor plane if it exists) would be in order :-) Cheers, Daniel > * 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(). > -- > 2.28.0 > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
