[Intel-gfx] [PATCH] drm/i915: A better maximum brightness for users.

[Shih-Yuan Lee (FourDollars)]

The PWM brightness level of Dell XPS 13 (2015) is from 10 to 937 however
the sysfs brightness level always starts from 0 so it is better to use
927 as the sysfs maximum brightness level and it becomes easier to map
from the PWM brightness level to the sysfs brightness level.

Signed-off-by: Shih-Yuan Lee (FourDollars) <sylee at canonical.com>
---
 drivers/gpu/drm/i915/intel_panel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index a24df35..697fd4d 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1211,7 +1211,7 @@ static int intel_backlight_device_register(struct intel_connector *connector)
 	 * Note: Everything should work even if the backlight device max
 	 * presented to the userspace is arbitrarily chosen.
 	 */
-	props.max_brightness = panel->backlight.max;
+	props.max_brightness = panel->backlight.max - panel->backlight.min;
 	props.brightness = scale_hw_to_user(connector,
 					    panel->backlight.level,
 					    props.max_brightness);
-- 
1.9.1