Sorry, I think I lost track of this thread at some point and forgot about it. That said… On Friday, August 7th, 2020 at 3:06 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Fri, Aug 07, 2020 at 12:38:02PM +0300, Pekka Paalanen wrote: > > On Fri, 7 Aug 2020 11:07:06 +0200 > > Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > 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. > > > > There could be multiple primary planes *usable* for a specific CRTC but > > just one used at a time, right? > > I'm not sure what you mean here, the crtc->primary link is invariant over > the lifetime of a driver load. You can't pick a different one, that's set > at driver init before drm_dev_register (and hence before userspace ever > sees anything). OK. I'm personally not very interested in documenting legacy bits, so I'll skip that. I'm mainly interested here in making it clear possible_crtcs for a primary plane can have more than one bit set. Because of the paragraph in the current docs, some user-space developers have understood "more than one bit set in possible_crtcs for a primary plane is a kernel bug". I'll send a v2 that makes it clear these pointers are for legacy uAPI. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
