Comment 233 for bug 1098216

Hi Peter,

(In reply to comment #106)
> I'm a little bit out-of-date, do I sume up correctly?

Yes, almost :-)

>
> The past:
> ACPI in-kernel handles hotkeys and passes it events to ACPI_BACKLIGHT (other
> drivers didn't work in this way) or userspace

The event is always sent to user space no matter if ACPI video driver will handle the event or not. So if ACPI video driver handles this event and user space also handles this event, the brightness level will go more steps on one hotkey press.

> The future:
> ACPI in-kernel handles hotkeys and passes it events to userspace, which
> passes
> it to $RANDOM_DRIVER

Yes, at least this is the case here. Since ACPI video's backlight interface is removed, the video driver will not handle brightness change on receiving an event.

>
> If that is correct: Could probably Systemd provide a hook for brightness,
> similiar to HANDLELIDSWITCH?
> see here: https://wiki.archlinux.org/index.php/Systemd#ACPI_power_management
>
> NAME could be:
> HANDLEBRIGHTNESS (without the extension KEY or KEYS, maybe it is a sensor or
> whatever...)
>
> This would allow for a environment agnositic approach, i.e. it works
> out-of-the
> box with the TTY, X11, Wayland and the different desktops. The backlight
> brigthness would be modifiable with the hotkeys always. If GNOME, KDE or XFCE
> handles the hotkeys itself, it could "inhibit" the HANDLE and uses it own
> facilities for power-management.

I think this is a good idea.