Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux

[linux-imx.git] / drivers / gpu / drm / i915 / intel_panel.c

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 67e2c1f1c9a8309b809c35f32395e26e67236992..5950888ae1d00bd7cf70ebb18d5595ee0ee8446e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -497,8 +497,11 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level, u32 max)
                goto out;
        }
 
-       /* scale to hardware */
-       level = level * freq / max;
+       /* scale to hardware, but be careful to not overflow */
+       if (freq < max)
+               level = level * freq / max;
+       else
+               level = freq / max * level;
 
        dev_priv->backlight.level = level;
        if (dev_priv->backlight.device)
@@ -515,6 +518,17 @@ void intel_panel_disable_backlight(struct drm_device *dev)
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long flags;
 
+       /*
+        * Do not disable backlight on the vgaswitcheroo path. When switching
+        * away from i915, the other client may depend on i915 to handle the
+        * backlight. This will leave the backlight on unnecessarily when
+        * another client is not activated.
+        */
+       if (dev->switch_power_state == DRM_SWITCH_POWER_CHANGING) {
+               DRM_DEBUG_DRIVER("Skipping backlight disable on vga switch\n");
+               return;
+       }
+
        spin_lock_irqsave(&dev_priv->backlight.lock, flags);
 
        dev_priv->backlight.enabled = false;