On Fri, Aug 05, 2016 at 01:16:55AM +0200, Enrico Weigelt, metux IT consult wrote: > On 04.08.2016 09:50, Daniel Vetter wrote: > > Hi, > > > One problem with 2d blitters is that there's no common userspace > > interface, but many: Xrender, hwc, old X drawing api, various attempts by > > khronos to standardize something, cairo, ... > > We're talking about userland APIs, not kernel->userland interfaces. > For userland APIs, I'm right now primarily interested in cairo > (using it for my tiny widget toolkit) ... but I'm also thinking about > setting X ontop of someting cairo-alike some day - or making gallium > that layer. > > > It's probably worse than video decoding even, and definitely not like > > on the 3d side where there's GL (and now vulkan) and that's it. > > On video side we have v4l for the kernel interface and gst as userland > framework ... looks like a good compromise to me. > > > So you you'll end up with tons of glue code everywhere anyway. > > Actually, I'd like to get the glue code smaller. Putting both cairo > and X onto the common driver base (something that's somewhere between > xorg video drivers and cairo surface backends) seems a good way to go, > even though there'll be a lot of work to do for that. > > > Adding yet another kernel uapi doesn't help, but forcing it to be generic > > will make sure it's inefficient. Which means someone else then will > > create another one. > > hmm, I'm not yet convinced that it necessarily will be inefficient. > > To clarify the scope: I'm talking only about _dedicated_ units, which > are completely orthogonal to complex gpus (basicly, just specialized > dma controllers). > > I personally don't care so much whether it's in DRM, V4L or whatever. > DRM just seemed to be a good place to me. > > By the way: as the number of such controllers increases, for dozens > of different things, eg. IO, crypto, etc., and in many cases they're > able to directly access the same memory, I got the feeling that we > should generalize gems even further, so that they could be any kind > of buffer that may be passed to any kind of device. (hmm, reminds me > on some ancient mainframe concepts). > > > If the blitter is always attached to the display block just add a few gem > > based ioctls there (like with desktop gpus) for submitting blit workloads. > > Otherwise new driver I guess. > > hmm, can I use gems outside DRM ? > eg. would it be possible to write an storage controller driver that > directly accesses an some gem (eg. let the controller write out an > gem object) ? Of course. In drm you can export/import gem buffers from to dma-buf. See https://dri.freedesktop.org/docs/drm/gpu/drm-mm.html#prime-buffer-sharing Cheers, 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
