Re: [PATCH v2] platform/x86: asus-wmi: Add keyboard backlight toggle support

From: Darren Hart
Date: Mon Jun 04 2018 - 21:59:22 EST

On Mon, Jun 04, 2018 at 11:27:43AM +0200, Benjamin Berg wrote:
> Hi,
> On Thu, 2018-05-24 at 16:33 +0800, Chris Chiu wrote:
> > I've made my change to set the brightness level directly in the
> > driver, but the
> > OSD doesn't show correctly correspond to the level value. The brightness shows
> > OK in /sys/class/led/xxxx/brighness but the OSD always shows level 0. I thought
> > GNOME should read the brightness from /sys before showing OSD?
> Sorry for the late response.
> There is a special mechanism to report that the HW changed the
> brightness. This works using the "brightness_hw_changed" sysfs
> attribute. So you will need to set the LED_BRIGHT_HW_CHANGED flag on
> the LED and then call led_classdev_notify_brightness_hw_changed to make
> it work.
> Userspace should correctly show the OSD when this is done.

This makes sense. Userspace can't be aware of every platforms sys files,
so there needs to be a common mechanism. LED_BRIGHT_HW_CHANGED makes

Darren Hart
VMware Open Source Technology Center