Hi,
On Fri, 11 Oct 2019 at 08:46, Daniel Vetter daniel@ffwll.ch wrote:
On Thu, Oct 10, 2019 at 7:32 PM Ayan Halder Ayan.Halder@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