Take Dell XPS 13 (2015) as an example. The vbt min 10 out of [0..255]. The PWM max is 937 so the corresponding PWM min is 37 (10*937/256). This commit makes the sysfs brightness 1 map to the PWM brightness 37 and 100 map to the PWM brightness 937. Signed-off-by: Shih-Yuan Lee (FourDollars) <sylee@xxxxxxxxxxxxx> --- drivers/gpu/drm/i915/intel_panel.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index a24df35..8652ce2 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -1207,11 +1207,12 @@ static int intel_backlight_device_register(struct intel_connector *connector) memset(&props, 0, sizeof(props)); props.type = BACKLIGHT_RAW; - /* - * Note: Everything should work even if the backlight device max - * presented to the userspace is arbitrarily chosen. - */ - props.max_brightness = panel->backlight.max; + /* Setting max to fixed 100 if the range is large enough. */ + if (panel->backlight.max > panel->backlight.min + 99) + props.max_brightness = 100; + else + props.max_brightness = panel->backlight.max - panel->backlight.min; + props.brightness = scale_hw_to_user(connector, panel->backlight.level, props.max_brightness); @@ -1414,6 +1415,8 @@ static u32 get_backlight_min_vbt(struct intel_connector *connector) struct drm_device *dev = connector->base.dev; struct drm_i915_private *dev_priv = dev->dev_private; struct intel_panel *panel = &connector->panel; + u32 pwm_min; + u32 pwm_step; int min; WARN_ON(panel->backlight.max == 0); @@ -1432,7 +1435,22 @@ static u32 get_backlight_min_vbt(struct intel_connector *connector) } /* vbt value is a coefficient in range [0..255] */ - return scale(min, 0, 255, 0, panel->backlight.max); + pwm_min = scale(min, 0, 255, 0, panel->backlight.max); + + /* Calculate the PWM step */ + if (panel->backlight.max > pwm_min + 99) + pwm_step = scale(1, 0, 99, 0, panel->backlight.max - pwm_min); + else + pwm_step = 1; + + /* + * Because sysfs brightness 0 is used to turn off the backlight, we need step + * down a little bit to make sysfs brightness 1 match the lowest brightness. + */ + if (pwm_min >= pwm_step) + pwm_min -= pwm_step; + + return pwm_min; } static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unused) -- 1.9.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
