bug#22952: Backlight brightness keys in GDM and MATE require password authentication

["pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de>]

On Wed, Nov 18, 2020 at 10:14:32PM +0100, Marius Bakke wrote:
> To work around it locally, try adding:
> 
>   (simple-service 'gsd-polkit polkit-service-type
>                   (list gnome-settings-daemon))
> 
> to the (services ...) section of your system configuration.

Thank you.  You are correct for GDM.  Adding this fixes changing the
backlight in GDM.  Perhaps the GDM service should extend the polkit
service like that.  It also does not conflict with adding a
gnome-service-type.

MATE still complains.  Without changing services, normally both on the
first log-in to MATE and on subsequent log-ins, when pressing the keys
to change the backlight, a message window still tells me that
/gnu/store/5kmmwc9q23lihpy3nv2knbvsr9qv2aln-mate-power-manager-1.24.2/sbin/mate-power-backlight-helper
needs to be authenticated as the super user; I need to enter the
password.

Only with gnome-service-type and when not removing the GDM service,
after GDM (which uses the gsd), on the first log-in to the MATE
desktop, the backlight keys do nothing at all.  When I try to log out,
it says Power Manager is not responding.  When I force the log-out
despite the Power Manager, then log back in, I again get the message
each time I press the backlight keys.

I added:

(simple-service 'mate-power-polkit polkit-service-type
                (list mate-power-manager))

It does not work.

Regards,
Florian