linux-kernel - Re: WARNING: CPU: 4 PID: 863 at include/drm/drm_crtc.h:1577 drm_helper_choose_encoder

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Message-ID: <20150923144450.GD3383@phenom.ffwll.local>
Date:	Wed, 23 Sep 2015 16:44:50 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Daniel Vetter <daniel@...ll.ch>,
	Alex Deucher <alexdeucher@...il.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	Maling list - DRI developers 
	<dri-devel@...ts.freedesktop.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: WARNING: CPU: 4 PID: 863 at include/drm/drm_crtc.h:1577
 drm_helper_choose_encoder_dpms+0x88/0x90()

On Wed, Sep 23, 2015 at 10:59:51AM +0200, Borislav Petkov wrote:
> On Wed, Sep 23, 2015 at 09:25:23AM +0200, Daniel Vetter wrote:
> > Strange thing is that I've tested this on a radeon over here and I don't
> > see this backtrace ... wut. Below diff should appease the backtraces at
> > least.
> 
> Doesn't look like it.

sorry I sprinkled the locking stuff in the wrong places. Still confused
why the resume side doesn't blow up anywhere ... Oh well. New patch below.

Thanks, Daniel

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index d8319dae8358..f3f562f6d848 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1573,10 +1573,12 @@ int radeon_suspend_kms(struct drm_device *dev, bool suspend, bool fbcon)
 
 	drm_kms_helper_poll_disable(dev);
 
+	drm_modeset_lock_all(dev);
 	/* turn off display hw */
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 		drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF);
 	}
+	drm_modeset_unlock_all(dev);
 
 	/* unpin the front buffers and cursors */
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
@@ -1734,9 +1736,11 @@ int radeon_resume_kms(struct drm_device *dev, bool resume, bool fbcon)
 	if (fbcon) {
 		drm_helper_resume_force_mode(dev);
 		/* turn on display hw */
+		drm_modeset_lock_all(dev);
 		list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 			drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
 		}
+		drm_modeset_unlock_all(dev);
 	}
 
 	drm_kms_helper_poll_enable(dev);
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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