On Wed, Apr 27, 2016 at 2:39 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Tue, Apr 26, 2016 at 01:48:02PM -0700, Greg Hackmann wrote: >> On 04/26/2016 01:05 PM, Daniel Vetter wrote: >> >On Tue, Apr 26, 2016 at 09:55:06PM +0300, Ville Syrjälä wrote: >> >>On Tue, Apr 26, 2016 at 08:23:46PM +0200, Daniel Vetter wrote: >> >>>On Tue, Apr 26, 2016 at 08:40:45PM +0300, Ville Syrjälä wrote: >> >>>But really the reason for per-plane is hw composer from >> >>>Android. I don't see any point in designing an api that's needlessly >> >>>different from what the main user expects (even if it may be silly). >> >> >> >>What are they doing that can't stuff the fences into an array >> >>instead of props? >> > >> >The hw composer interface is one in-fence per plane. That's really the >> >major reason why the kernel interface is built to match. And I really >> >don't think we should diverge just because we have a slight different >> >color preference ;-) >> > >> >As long as you end up with a pile of fences somehow it'll work. >> >-Daniel >> > >> >> The relationship between layers and fences is only fuzzy and indirect >> though. The relationship is really between the buffer you're displaying on >> that layer, and the fence representing the work done to render into that >> buffer. SurfaceFlinger just happens to bundle them together inside the same >> struct hwc_layer_1 as an API convenience. >> >> Which is kind of splitting hairs as long as you have a 1-to-1 relationship >> between layers and DRM planes. But that's not always the case. >> >> A (per-CRTC?) array of fences would be more flexible. And even in the cases >> where you could make a 1-to-1 mapping between planes and fences, it's not >> that much more work for userspace to assemble those fences into an array >> anyway. > > I'm ok with an array too if that's what you folks prefer (it's meant to be > used by you after all). I just don't want just 1 fence for the entire op, > forcing userspace to first merge them all together. That seems silly. I was kinda more a fan of array too, if for no other reason that to be consistent w/ how out-fences work. (And using property just for in-fence seemed slightly weird/abusive to me) > One side-effect of that is that we'd also have to rework all the internal > bits and move fences around in atomic. Which means change a pile of > drivers. Not sure that's worth it, but I'd be ok either way really. hmm, well we could keep the array per-plane (and if one layer is using multiple planes, just list the same fd multiple times).. then it mostly comes down to changes in the ioctl fxn itself. BR, -R > -Daniel > -- > 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 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
