Reported by Michael Mrozek, Jun 14, 2018
I haven't checked that, so it could be this already has been done properly (please close the issue in this case). I noticed on my Thinkpad (which also has keyboard backlight) that Linux knows about both about the display and keyboard backlight as well as the allowed values. KDE clearly recognizes this as keyboard backlight (it shows a small keyboard symbol with a slider to change the backlight). Not sure if we setup our LEDs so that Linux knows this is a keyboard (or LCD) backlight. If not, this should be done.
Comment 1 by Andreas Kemnade, Feb 16, 2019
what is done now is that display backlight is coupled to display so if display is turned off, backlight is also turned off. accepted upstream for gta04 lcd, but missed the merge window for 5.1 (closed at 5.0-rc5), similar solution has been developed for pyra lcd. But that does not influence userspace decision which backlight belongs to what. No idea if there is work needed.
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