drm/i915: Add lock on drm_helper_resume_force_mode
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>
Cc: stable@kernel.org
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 19d55bc..dfa55e7 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -538,7 +538,9 @@
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);