| Message ID | 1893554f-cdd7-4069-9b66-f47a155612e2@ti.com |
|---|---|
| State | New |
| Headers | show |
2016-12-12 12:26 GMT+01:00 Jyri Sarha <jsarha@ti.com>: > On 12/05/16 19:07, Bartosz Golaszewski wrote: >> 2016-12-05 12:01 GMT+01:00 Bartosz Golaszewski <bgolaszewski@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. > Indeed sounds like a probable cause. >> 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. > Sure, I just did it to see if it would change anything. >> 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? > No it doesn't - I'm still getting the warning. Thanks, Bartosz
From 35957a10ed12188a3f8ed63c694929eb1bb3d9b6 Mon Sep 17 00:00:00 2001 From: Jyri Sarha <jsarha@ti.com> 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@ti.com> --- 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