On 12/05/16 19:07, Bartosz Golaszewski wrote: > 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 >
Sorry, I almost forgot about this problem. > This seems like some END_OF_FRAME0 interrupt-related race condition. I can not see any race related to vblank event sending. The drm_modeset_lock_crtc() is there exactly for all ongoing operations to complete before shutting down the crtc. I think the problem is a missing END_OF_FRAME0 interrupt when sync lost interrupt flood happens. > Increasing the timeout in drm_atomic_helper_wait_for_vblanks() from 50 > to 100 and dropping drm_modeset_lock_crtc()/drm_modeset_unlock_crtc() Not taking the lock causes drm_crtc_vblank_off() to be called in tilcdc_crtc_disable(), before the time out happens. However, this is racy because there is a pending commit still on going and executing in parallel with the recovery work. > 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 I wonder what happens in that 10% off the times when when that does not help... > have been unable to figure out a reliable solution today though. > Does the attached patch help with the issue? Best regards, Jyri -------------- next part -------------- A non-text attachment was scrubbed... Name: 0001-drm-tilcdc-Send-pendig-vblank-event-before-recovery-.patch Type: text/x-patch Size: 1489 bytes Desc: not available URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20161212/b3f8c50b/attachment.bin>
