drm/i915: panel: invert brightness via parameter

[pandora-kernel.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 04d79fd..d38a783 100644 (file)
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -28,6 +28,7 @@
  *      Chris Wilson <chris@chris-wilson.co.uk>
  */
 
+#include <linux/moduleparam.h>
 #include "intel_drv.h"
 
 #define PCI_LBPC 0xf4 /* legacy/combination backlight modes */
@@ -191,6 +192,20 @@ u32 intel_panel_get_max_backlight(struct drm_device *dev)
        return max;
 }
 
+static bool i915_panel_invert_brightness;
+MODULE_PARM_DESC(invert_brightness, "Invert backlight brightness, please "
+       "report PCI device ID, subsystem vendor and subsystem device ID "
+       "to dri-devel@lists.freedesktop.org, if your machine needs it. "
+       "It will then be included in an upcoming module version.");
+module_param_named(invert_brightness, i915_panel_invert_brightness, bool, 0600);
+static u32 intel_panel_compute_brightness(struct drm_device *dev, u32 val)
+{
+       if (i915_panel_invert_brightness)
+               return intel_panel_get_max_backlight(dev) - val;
+
+       return val;
+}
+
 u32 intel_panel_get_backlight(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
@@ -211,6 +226,7 @@ u32 intel_panel_get_backlight(struct drm_device *dev)
                }
        }
 
+       val = intel_panel_compute_brightness(dev, val);
        DRM_DEBUG_DRIVER("get backlight PWM = %d\n", val);
        return val;
 }
@@ -228,6 +244,7 @@ static void intel_panel_actually_set_backlight(struct drm_device *dev, u32 level
        u32 tmp;
 
        DRM_DEBUG_DRIVER("set backlight PWM = %d\n", level);
+       level = intel_panel_compute_brightness(dev, level);
 
        if (HAS_PCH_SPLIT(dev))
                return intel_pch_panel_set_backlight(dev, level);