2016-12-05 12:01 GMT+01:00 Bartosz Golaszewski <bgolaszewski at baylibre.com>: > Hi Jyri, > > I pulled your recent tilcdc pull request on top of v4.9 and Sekhar's > davinci branch (+ vga dac DT)[1]. > > I'm getting "vblank wait timed out" errors when running simple modetest[2]. > > This error happened before with the drm_bridge series[3], but went > away at one of the subsequent patch versions. > > Could you please verify that you see the same error and advise on what > could be the reason? I'm investigating on my own as well. > > Best regards, > Bartosz Golaszewski > > [1] https://github.com/brgl/linux/tree/tilcdc/modetest_error > [2] http://pastebin.com/rCM44Uds > [3] http://www.spinics.net/lists/dri-devel/msg123732.html
This seems like some END_OF_FRAME0 interrupt-related race condition. Increasing the timeout in drm_atomic_helper_wait_for_vblanks() from 50 to 100 and dropping drm_modeset_lock_crtc()/drm_modeset_unlock_crtc() in tilcdc_crtc_recover_work() makes the warning disappear. Also: calling drm_crtc_vblank_off() additionally before locking the crtc in tilcdc_crtc_recover_work() also seems to fix the issue 90% of times. I have been unable to figure out a reliable solution today though. Best regards, Bartosz Golaszewski
