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@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; }