On 12/05/16 19:07, Bartosz Golaszewski wrote: > 2016-12-05 12:01 GMT+01:00 Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>: >> 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
From 35957a10ed12188a3f8ed63c694929eb1bb3d9b6 Mon Sep 17 00:00:00 2001 From: Jyri Sarha <jsarha@xxxxxx> Date: Mon, 12 Dec 2016 12:44:47 +0200 Subject: [PATCH] drm/tilcdc: Send pendig vblank event before recovery work Send the pending vblank event without waiting for the END_OF_FRAME0 interrupt. Sometimes the END_OF_FRAME0 interrupt does not come when LCDC suffers from the sync lost flood and this causes a nasty warning in drm_atomic_helper_wait_for_vblanks(). Signed-off-by: Jyri Sarha <jsarha@xxxxxx> --- drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c index 9942b05..00ce9d2 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c @@ -566,9 +566,19 @@ static void tilcdc_crtc_recover_work(struct work_struct *work) struct tilcdc_crtc *tilcdc_crtc = container_of(work, struct tilcdc_crtc, recover_work); struct drm_crtc *crtc = &tilcdc_crtc->base; + struct drm_device *dev = crtc->dev; + struct drm_pending_vblank_event *event; + unsigned long flags; dev_info(crtc->dev->dev, "%s: Reset CRTC", __func__); + spin_lock_irqsave(&dev->event_lock, flags); + event = tilcdc_crtc->event; + tilcdc_crtc->event = NULL; + if (event) + drm_crtc_send_vblank_event(crtc, event); + spin_unlock_irqrestore(&dev->event_lock, flags); + drm_modeset_lock_crtc(crtc, NULL); if (!tilcdc_crtc_is_on(crtc)) -- 1.9.1
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