[ 20/42] drm/i915: Add lock on drm_helper_resume_force_mode

From: Greg KH
Date: Wed Apr 11 2012 - 19:35:15 EST


3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Sean Paul <seanpaul@xxxxxxxxxxxx>

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@xxxxxxxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-Off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/gpu/drm/i915/i915_drv.c | 2 ++
1 file changed, 2 insertions(+)

--- 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_devi
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);


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