drm/i915: protect backlight registers and data with a spinlock
Backlight data and registers are fiddled through LVDS/eDP modeset
enable/disable hooks, backlight sysfs files, asle interrupts, and register
save/restore. Protect the backlight related registers and driver private
fields using a spinlock.
The locking in register save/restore covers a little more than is strictly
necessary, including non-modeset case, for simplicity.
v2: Cover register access, save/restore, i915_read_blc_pwm_ctl() and code
paths leading there.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 63a7c36..5d3e9d7 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -138,6 +138,8 @@
struct drm_i915_private *dev_priv = dev->dev_private;
u32 val;
+ WARN_ON(!spin_is_locked(&dev_priv->backlight.lock));
+
/* Restore the CTL value if it lost, e.g. GPU reset */
if (HAS_PCH_SPLIT(dev_priv->dev)) {
@@ -218,6 +220,9 @@
{
struct drm_i915_private *dev_priv = dev->dev_private;
u32 val;
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev_priv->backlight.lock, flags);
if (HAS_PCH_SPLIT(dev)) {
val = I915_READ(BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
@@ -235,6 +240,9 @@
}
val = intel_panel_compute_brightness(dev, val);
+
+ spin_unlock_irqrestore(&dev_priv->backlight.lock, flags);
+
DRM_DEBUG_DRIVER("get backlight PWM = %d\n", val);
return val;
}
@@ -282,11 +290,14 @@
{
struct drm_i915_private *dev_priv = dev->dev_private;
u32 freq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev_priv->backlight.lock, flags);
freq = intel_panel_get_max_backlight(dev);
if (!freq) {
/* we are screwed, bail out */
- return;
+ goto out;
}
/* scale to hardware */
@@ -298,11 +309,16 @@
if (dev_priv->backlight.enabled)
intel_panel_actually_set_backlight(dev, level);
+out:
+ 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);
@@ -320,12 +336,17 @@
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);
@@ -375,6 +396,8 @@
*/
dev_priv->backlight.enabled = true;
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)
@@ -432,6 +455,7 @@
struct drm_device *dev = connector->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
struct backlight_properties props;
+ unsigned long flags;
intel_panel_init_backlight(dev);
@@ -441,7 +465,11 @@
memset(&props, 0, sizeof(props));
props.type = BACKLIGHT_RAW;
props.brightness = dev_priv->backlight.level;
+
+ spin_lock_irqsave(&dev_priv->backlight.lock, flags);
props.max_brightness = intel_panel_get_max_backlight(dev);
+ spin_unlock_irqrestore(&dev_priv->backlight.lock, flags);
+
if (props.max_brightness == 0) {
DRM_DEBUG_DRIVER("Failed to get maximum backlight value\n");
return -ENODEV;
