[PATCH 2/5] drm/i915: protect backlight enable and level with spinlock

[jani.nikula at intel.com (Jani Nikula)]

Backlight is fiddled both through backlight sysfs files and asle
interrupts. Protect the relevant data.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h    |    1 +
 drivers/gpu/drm/i915/intel_panel.c |   16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5e38a2c..2e59610 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -943,6 +943,7 @@ typedef struct drm_i915_private {
 	struct {
 		int level;
 		bool enabled;
+		spinlock_t lock;
 		struct backlight_device *device;
 	} backlight;
 
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 0e7e873..2a95297 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -285,6 +285,9 @@ static void intel_panel_actually_set_backlight(struct drm_device *dev, u32 level
 void intel_panel_set_backlight(struct drm_device *dev, u32 level)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
 
 	dev_priv->backlight.level = level;
 	if (dev_priv->backlight.device)
@@ -292,11 +295,16 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level)
 
 	if (dev_priv->backlight.enabled)
 		intel_panel_actually_set_backlight(dev, level);
+
+	spin_unlock_irqrestore(&dev_priv->backlight.lock, flags);
 }
 
 void intel_panel_disable_backlight(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
 
 	dev_priv->backlight.enabled = false;
 	intel_panel_actually_set_backlight(dev, 0);
@@ -314,12 +322,17 @@ void intel_panel_disable_backlight(struct drm_device *dev)
 			I915_WRITE(BLC_PWM_PCH_CTL1, tmp);
 		}
 	}
+
+	spin_unlock_irqrestore(&dev_priv->backlight.lock, flags);
 }
 
 void intel_panel_enable_backlight(struct drm_device *dev,
 				  enum pipe pipe)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
 
 	if (dev_priv->backlight.level == 0) {
 		dev_priv->backlight.level = intel_panel_get_max_backlight(dev);
@@ -372,12 +385,15 @@ set_level:
 	 */
 	if (!intel_panel_get_backlight(dev))
 		intel_panel_actually_set_backlight(dev, dev_priv->backlight.level);
+
+	spin_unlock_irqrestore(&dev_priv->backlight.lock, flags);
 }
 
 static void intel_panel_init_backlight(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	spin_lock_init(&dev_priv->backlight.lock);
 	dev_priv->backlight.level = intel_panel_get_backlight(dev);
 	dev_priv->backlight.enabled = dev_priv->backlight.level != 0;
 }
-- 
1.7.9.5