From: Sean Paul <seanpaul@chromium.org>
Date: Fri, 23 Mar 2012 12:52:58 +0000 (-0400)
Subject: drm/i915: Add lock on drm_helper_resume_force_mode
X-Git-Tag: firefly_0821_release~7541^2~1422
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4482e98a406487cf1adadd88d23b99e40ca44aa8;p=firefly-linux-kernel-4.4.55.git

drm/i915: Add lock on drm_helper_resume_force_mode

commit 927a2f119e8235238a2fc64871051b16c9bdae75 upstream.

i915_drm_thaw was not locking the mode_config lock when calling
drm_helper_resume_force_mode. When there were multiple wake sources,
this caused FDI training failure on SNB which in turn corrupted the
display.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 2d3e16b3a09a..111686ada271 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -442,7 +442,9 @@ static int i915_drm_thaw(struct drm_device *dev)
 		drm_irq_install(dev);
 
 		/* Resume the modeset for every activated CRTC */
+		mutex_lock(&dev->mode_config.mutex);
 		drm_helper_resume_force_mode(dev);
+		mutex_unlock(&dev->mode_config.mutex);
 
 		if (IS_IRONLAKE_M(dev))
 			ironlake_enable_rc6(dev);