add ".prepare_fb = drm_gem_fb_prepare_fb," in "drm_plane_helper_funcs" solve my flicker problem on Allwinner A64. Thanks, Qiang On Sun, Nov 18, 2018 at 8:14 PM Qiang Yu <yuq825@xxxxxxxxx> wrote: > > 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
