On Fri, Jan 15, 2021 at 12:06 PM Simon Ser <cont...@emersion.fr> wrote: > > On Tuesday, December 22nd, 2020 at 2:59 PM, Daniel Vetter <dan...@ffwll.ch> > wrote: > > > > + * type: > > > + * Immutable property describing the type of the plane. > > > + * > > > + * For user-space which has enabled the > > > &DRM_CLIENT_CAP_UNIVERSAL_PLANES > > > > s/UNIVERSAL_PLANES/ATOMIC/ here? > > > > With just universal planes you don't have atomic test-only. But I guess it > > also works as-is, I'm just not entirely clear what you want to state here. > > Right. This paragraph was written when I wasn't aware about ATOMIC implicitly > enabling UNIVERSAL_PLANES. Fixed in v5. > > > > + * 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 superseded by 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. > > > Note that > > > + * &DRM_CLIENT_CAP_UNIVERSAL_PLANES is implicitly enabled by > > > + * &DRM_CLIENT_CAP_ATOMIC. > > > + * > > > + * 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. > > > > Empty line here for reading comfort in plain text? Same below. > > > > Since you mention formats below, I also wonder whether we should state > > here that xrgb8888 is generally supported, worst case through software > > emulation. That's defacto the uapi we have to adhere to. > > I wonder. If a new driver decides not to support XRGB8888, that wouldn't be a > kernel regression because it's about new hardware. Do we want to formally lock > future drivers into XRGB8888 support? Or do we want to open the door for a > driver to break this assumption, even if most user-space won't work on the new > hardware? > > I guess all of this is mostly theoretical at this point.
It's been practical since a few years, since a lot of the simple panels we've added don't support xrgb8888. That's why we have the fairly good horror show of format conversions in drm_format_helper.c. And we've done this because too much general distro userspace just keels over real bad if xrgb8888 doesn't work. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
