On Mon, Nov 9, 2015 at 6:17 PM, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
On Mon, 09 Nov 2015, "Shih-Yuan Lee (FourDollars)" <sylee@xxxxxxxxxxxxx> wrote:That might not be a good idea for the backward compatibility.
> 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.
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) <sylee@xxxxxxxxxxxxx>
> ---
> 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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