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

[Jani Nikula]

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

Signed-off-by: Jani Nikula <jani.nik...@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

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