On Mon, Nov 9, 2015 at 6:17 PM, Jani Nikula <jani.nik...@linux.intel.com> wrote:
> On Mon, 09 Nov 2015, "Shih-Yuan Lee (FourDollars)" <sy...@canonical.com> > wrote: > > 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. > > We've been thinking we should provide a fixed range to userspace > instead. Say, 0-100. > > BR, > Jani. > > > > That might not be a good idea for the backward compatibility. However I saw some message as the following. [ 3.402233] [drm:parse_lfp_backlight] VBT backlight PWM modulation frequency 200 Hz, active high, min brightness 10, level 255 Does it mean the brightness range is also defined in the BIOS? Regards, $4 > > > > > Signed-off-by: Shih-Yuan Lee (FourDollars) <sy...@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); > > -- > Jani Nikula, Intel Open Source Technology Center > -- Shih-Yuan Lee (FourDollars) | Software Engineer | Commercial Engineering - PC & Core Taipei | Ubuntu Engineering and Services | Canonical
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