[PATCH] drm/i915: Avoid drm_atomic_state_put(NULL) in intel_display_resume

[Chris Wilson]

intel_display_resume() may be called without a atomic state to restore,
i.e. dev_priv->modeset_reset_restore state is NULL. One such case is
following a lid open/close event and the forced modeset in
intel_lid_notiy().

Reported-by: Stefan Seyfried <stefan.seyfried@xxxxxxxxxxxxxx>
Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: <drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx> # v4.10-rc1+
---
 drivers/gpu/drm/i915/intel_display.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3dc8724df400..260bbe8881e6 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -17024,7 +17024,8 @@ void intel_display_resume(struct drm_device *dev)
 
 	if (ret)
 		DRM_ERROR("Restoring old state failed with %i\n", ret);
-	drm_atomic_state_put(state);
+	if (state)
+		drm_atomic_state_put(state);
 }
 
 void intel_modeset_gem_init(struct drm_device *dev)
-- 
2.11.0