Buster upgrade introduces power manager DBus errors
Please help me interpret some error messages in the xfce4-power-manager
daemon log. I collected these logs because, when I upgraded from Debian 9
stretch to Debian 10 buster, the screen backlight adjustment on my
Panasonic CF-19 laptop no longer works, and the various sleep modes have
become erratic.
Among other things, I tried collecting the logs when the power manager
daemon restarts:
# xfce4-power-manager -q
# xfce4-power-manager --nodaemon --debug
The logs in stretch and buster look very similar, however there are three
new warning and one critical message in the log under buster.
The three new warnings are at the very beginning of the log:
** (xfce4-power-manager:1643): WARNING **: 01:14:35.473: Failed to get
name owner: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Could
not get owner of name 'org.freedesktop.PowerManagement': no such name
** (xfce4-power-manager:1643): WARNING **: 01:14:35.473: Failed to get
name owner: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Could
not get owner of name 'org.xfce.PowerManager': no such name
(xfce4-power-manager:1643): GLib-GObject-WARNING **: 01:14:35.489:
../../../gobject/gsignal.c:2523: signal 'Changed' is invalid for instance
'0x558c1e1d2220' of type 'GDBusProxy'
TRACE[xfpm-main.c:205] xfpm_start(): Starting the power manager
...
The critical message is in the middle of the startup messages:
...
(xfce4-power-manager:1643): GLib-CRITICAL **: 01:14:35.512: g_error_free:
assertion 'error != NULL' failed
...
Please tell me what these messages mean and what I should try next to fix
this.
Some additional information:
By the screen backlight adjustment no longer working, I mean, after
upgrading to buster, neither the laptop's brightness buttons nor the power
manager applet in the xfce tray are able to change the brightness. The
laptop buttons still do work during an early part of the boot process.
By sleep modes being erratic, I mean the laptop going to sleep and
recovering usually works, but occasionally goes to a mode (screen lock
versus suspend versus hibernate versus powerdown) other than intended. Of
course, powering down when you still have applications open is most
frustrating. So far, I haven't been able to figure out how to make this
problem reproducible. Have been focusing on the brightness problem since
it is reproducible.
I should mention the warnings that occur under both stretch and buster:
...
(xfce4-power-manager:1643): xfce4-power-manager-WARNING **: 01:14:35.506:
could not map keysym 1008ffa8 to keycode
** (xfce4-power-manager:1643): WARNING **: 01:14:35.512: No outputs have
backlight property
xfce4-power-manager-Message: 01:14:35.543: Set kernel brightness switch to
0
(xfce4-power-manager:1643): xfce4-power-manager-WARNING **: 01:14:35.547:
Failed to get keyboard max brightness level :
GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface
“org.freedesktop.UPower.KbdBacklight” on object at path
/org/freedesktop/UPower/KbdBacklight
...
Which I interpret the first message to mean Xfce's notion of the laptop's
key map is not quite right.
The others I think mean power manager first tries to control the backlight
via an X server property. When that fails, it tries UPower. When that
fails, it falls back to a method that provides no feedback whether it
works or not. Whatever that method is, it works under stretch but not
buster. Does this interpretation sound reasonable? Anyhow, it works fine
under stretch despite these warnings. Would like to understand them, but
if you can help me understand the warnings from buster, or for that
matter, getting backlight and sleep working without understanding the
warnings, that would be most appreciated. I can send the full logs, if
that would be helpful.
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