I find the reservation object will be created when: dma_buf_export if no reservation object created when buffer object creation. And the implicit fence can be synced before display in: drm_gem_fb_prepare_fb but seems most display driver doesn't call this function. Regards, Qiang On Sun, Nov 18, 2018 at 10:43 AM Qiang Yu <yuq825@xxxxxxxxx> wrote: > > Hi Eric and Wladimir, > > GPU driver like VC4, Etnaviv and Lima only do rendering and left display > to other DRM display drivers. So there should be a render/display sync > problem for these drivers. > > As I know, there are two ways: implicit and explicit described here: > https://www.collabora.com/news-and-blog/blog/2016/09/13/mainline-explicit-fencing-part-1/ > > The implicit way need the display DRM driver wait on the reservation object > associated with that framebuffer before display it, the reservation > object contains > fence which is added by render DRM driver to indicate render finish: > https://www.phoronix.com/scan.php?page=news_item&px=AMDGPU-Intel-4.9-PRIME-Ex-Patch > > I investigate a bit into these DRM display drivers using CMA GEM helpers, > seems there's no reservation object at all, so it should be impossible to > support implicit sync. > > Although explicit way is better, there are still some apps not support it like > kodi-gbm. So how do VC4+PL111 and Etnaviv+IMX solve this sync problem, > and do these drivers support implicit sync? > > Thanks, > Qiang _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
