On Tue, Feb 02, 2016 at 09:34:11AM +0000, Tvrtko Ursulin wrote: > > On 01/02/16 17:57, Ville Syrjälä wrote: > >On Mon, Feb 01, 2016 at 05:44:42PM +0000, Tvrtko Ursulin wrote: > >> > >>On 01/02/16 17:16, Zanoni, Paulo R wrote: > >>>Em Sex, 2016-01-29 às 21:06 +0200, Ville Syrjälä escreveu: > >>>>On Fri, Jan 29, 2016 at 04:46:30PM -0200, Paulo Zanoni wrote: > >>>>>The interesting thing is that if we don't do this, we still get a > >>>>>Y tiled framebuffer, but there won't be a fence around it, which > >>>>>makes > >>>>>the GTT mmaps less interesting. Is this a Kernel bug? > >>>> > >>>>I think some tests currently depend on not having a fence for Y tiled > >>>>fbs. So this could break stuff. > >>> > >>>Do you have any additional information that could help me discover > >>>which ones? A quick look on the IGT tests mentioning tiling didn't > >>>point anything obvious. > >>> > >>>Besides, I think it's probably not a good idea to have such a high > >>>level helper function behaving differently depending on the tiling > >>>type, I'd vote to either call set_tiling on both or on none. > >> > >>Noticed the thread by accident. :) > >> > >>I can't help with the question of which tests might be affected by this. > >>Some low level ones like kms_addfb don't use the fb helpers so they > >>shouldn't be. Can't remember if any other would be. > >> > >>But just a little bit of background: > >> > >>Basically with the introduction of Y tiled (and Yf) scanout in Gen9 we > >>have forked the path and destroyed the coupling between obj->tiling and > >>framebuffer tiling. > >> > >>The X special casing in create_bo_for_fb is for compatibility with old > >>userspace, but going forward it was decided fb modifiers should be used > >>to tell the driver about tiling and get/set_tiling ioctl is about > >>fencing and only that. > >> > >>Paths implemented in IGT back then were rendering to Y and Yf tiling fbs > >>via a temporary linear surface which is then blitted (blit?) to the real > >>fb obj. (With the blitter doing the appropriate transformation.) > >> > >>So in that respect adding Y tiling to create_bo_for_fb would be wrong > >>because it is not aligned with the above, and also you cannot support Yf > >>this way at all. > >> > >>But I do agree this creates a problem for some use cases within the IGT > >>since the fb and backing obj are created atomically and once that is > >>done you cannot fiddle with obj->tiling (aka fencing). > > > >I suppose we could either make it easier to create the obj and fb > >separately, or we could add a parameter to the fb funcs to indicate > >whether we want a fence or not. > > Either way sounds good to me. Will depend on whatever fits better with what > Paulo is working on at the moment. I'm ok with not tiling by default for anything but X-tiled in the igt_fb code. Users can just call set_tiling on the underlying bo if they want it, but in the shiny new world of Yf/Ys we should by default not use gtt mmaps really for anything. See also some of the changes planned and then cancelled/delayed for future products, where the gtt might go poof entirely. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
