Hi, On Fri, 11 Oct 2019 at 08:46, Daniel Vetter <dan...@ffwll.ch> wrote: > On Thu, Oct 10, 2019 at 7:32 PM Ayan Halder <ayan.hal...@arm.com> wrote: > > On Thu, Oct 10, 2019 at 03:41:15PM +0200, Neil Armstrong wrote: > > > Sorry I don't understand, you ask me to limit AFBC to ABGR8888 ? > > > > Apologies for the confusion, as per the link, the formats which are > > suggested with AFBC_FORMAT_MOD_YTR are the BGR/ABGR formats (as > > listed in the 'AFBC formats' table) > > > > Thus, any other permutation of the components might make it incompatible > > with some other AFBC producers/consumers. > > Uh, that's not how this is supposed to be used. Drivers are meant to > expose _everything_ they support (bonus if you roughly sort it in > preference order). Userspace then computes the intersection of > modifiers/formats supported by all devices it needs to share a buffer > with. Allowing that was the entire point of modifiers, if we > artificially limit to the common denominator we're back "only linear > works everywhere".
Correct. A lot of userspace will select for format first, then find a modifier which can be used with that format. If userspace has specific knowledge of AFBC and decides that it prefers to use AFBC so will seek out an alpha format - and make sure everyone fills the channel solid - then that's fine. But that's putting the cart before the horse. Not exposing XRGB8888 on the primary plane will break a lot of userspace, so in this case AFBC would just never really be used. Cheers, Daniel _______________________________________________ dri-devel mailing list firstname.lastname@example.org https://lists.freedesktop.org/mailman/listinfo/dri-devel