On Wed, Apr 4, 2018 at 10:06 PM, Alexey Brodkin <Alexey.Brodkin at synopsys.com> wrote: > Hello, > > We're trying to use DisplayLink USB2-to-HDMI adapter to render GPU-accelerated graphics. > Hardware setup is as simple as a devboard + DisplayLink adapter. > Devboards we use for this experiment are: > * Wandboard Quad (based on IMX6 SoC with Vivante GPU) or > * HSDK (based on Synopsys ARC HS38 SoC with Vivante GPU as well) > > I'm sure any other board with DRM supported GPU will work, those we just used > as the very recent Linux kernels could be easily run on them both. > > Basically the problem is UDL needs to be explicitly notified about new data > to be rendered on the screen compared to typical bit-streamers that infinitely > scan a dedicated buffer in memory. > > In case of UDL there're just 2 ways for this notification: > 1) DRM_IOCTL_MODE_PAGE_FLIP that calls drm_crtc_funcs->page_flip() > 2) DRM_IOCTL_MODE_DIRTYFB that calls drm_framebuffer_funcs->dirty() > > But neither of IOCTLs happen when we run Xserver with xf86-video-armada driver > (see http://git.arm.linux.org.uk/cgit/xf86-video-armada.git/log/?h=unstable-devel). > > Is it something missing in Xserver or in UDL driver? Use the -modesetting driverr for UDL, that one works correctly. Kernel-driver specific X drivers are kinda deprecated, and stuff like this (and other bugfixes and improvements that don't propagate around) are the reason for that. -Daniel > > Regards, > Alexey > > > > > -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
