When controlling backlight devices via sysfs interface, user space
generally assumes the minimum level (0) still providing a brightness
that is usable by the user (probably due to the most commonly used
backlight device, acpi_videoX, behaving exactly like that). This doesn't
match the current behaviour of the intel_backlight control, though, as
the value 0 means 'backlight off'.
In order to make intel_backlight consistent to other backlight devices,
introduce a module parameter that allows shifting the 0 level of the
intel_backlight device. It's expressed in percentages of the maximum
level. The default is 5, which provides a backlight level that is barely
readable. Setting it to 0 restores the old behaviour.
Signed-off-by: Danny Baumann <dannybaumann at web.de>
---
drivers/gpu/drm/i915/intel_panel.c | 48 ++++++++++++++++++++++++++++++++------
1 file changed, 41 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_panel.c
b/drivers/gpu/drm/i915/intel_panel.c
index bee8cb6..5bad49d 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -395,10 +395,35 @@ intel_panel_detect(struct drm_device *dev)
}
#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+
+static int i915_panel_min_brightness_percent = 5;
+MODULE_PARM_DESC(min_sysfs_brightness, "Minimum brightness percentage settable
"
+ "via sysfs. This adjusts the brightness level of the value '0' in the "
+ "intel_backlight sysfs backlight interface.");
+module_param_named(min_sysfs_brightness,
+ i915_panel_min_brightness_percent, int, 0400);
+
+static int intel_panel_min_brightness(struct drm_device *dev)
+{
+ int max;
+
+ if (i915_panel_min_brightness_percent <= 0)
+ return 0;
+
+ max = intel_panel_get_max_backlight(dev);
+ if (i915_panel_min_brightness_percent >= 100)
+ return max;
+
+ return max * i915_panel_min_brightness_percent / 100;
+}
+
static int intel_panel_update_status(struct backlight_device *bd)
{
struct drm_device *dev = bl_get_data(bd);
- intel_panel_set_backlight(dev, bd->props.brightness);
+ int brightness =
+ bd->props.brightness + intel_panel_min_brightness(dev);
+
+ intel_panel_set_backlight(dev, brightness);
return 0;
}
@@ -406,7 +431,10 @@ static int intel_panel_get_brightness(struct
backlight_device *bd)
{
struct drm_device *dev = bl_get_data(bd);
struct drm_i915_private *dev_priv = dev->dev_private;
- return dev_priv->backlight_level;
+ int brightness =
+ dev_priv->backlight_level - intel_panel_min_brightness(dev);
+
+ return brightness;
}
static const struct backlight_ops intel_panel_bl_ops = {
@@ -419,16 +447,21 @@ int intel_panel_setup_backlight(struct drm_connector
*connector)
struct drm_device *dev = connector->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
struct backlight_properties props;
+ int max_brightness;
intel_panel_init_backlight(dev);
- memset(&props, 0, sizeof(props));
- props.type = BACKLIGHT_RAW;
- props.max_brightness = _intel_panel_get_max_backlight(dev);
- if (props.max_brightness == 0) {
+ max_brightness = _intel_panel_get_max_backlight(dev);
+ if (max_brightness == 0) {
DRM_DEBUG_DRIVER("Failed to get maximum backlight value\n");
return -ENODEV;
}
+
+ memset(&props, 0, sizeof(props));
+ props.type = BACKLIGHT_RAW;
+ props.max_brightness =
+ max_brightness - intel_panel_min_brightness(dev);
+
dev_priv->backlight =
backlight_device_register("intel_backlight",
&connector->kdev, dev,
@@ -440,7 +473,8 @@ int intel_panel_setup_backlight(struct drm_connector
*connector)
dev_priv->backlight = NULL;
return -ENODEV;
}
- dev_priv->backlight->props.brightness = intel_panel_get_backlight(dev);
+ dev_priv->backlight->props.brightness = intel_panel_get_backlight(dev)
+ - intel_panel_min_brightness(dev);
return 0;
}
--
1.8.1.4
