[ltp] Debian Wheezy w/XFCE screen brightness step value

Henrique de Moraes Holschuh linux-thinkpad@linux-thinkpad.org
Tue, 21 Feb 2012 12:45:57 -0200

On Mon, 20 Feb 2012, Nate Bargmann wrote:
> I put a fresh installation of Debian Wheezy (Testing) on my T60 a couple
> of weeks ago (long story) using XFCE desktop as the setup.  I've noted,

Disable acpi video and disable thinkpad-acpi brightness control.  This will
make sure no idiotic fluff in userspace will be able to screw with your
brightness control, unless it does it through X.org (which may or may not
control brightness, depends on the thinkpad model, and I don't recall
whether the T60 has EC-based brightness control or GPU-based brightness

You can actually ask thinkpad-acpi to rat out the PIDs of processes messing
with brightness values [through thinkpad-acpi], check the documentation.

> with some annoyance, that when I change the screen brightness with the
> Fn-Home/End keys that occasionally a graphical brightness icon appears
> and when it does, the screen is dimmed or brightened in multiple steps.
> The T60 has eight brightness levels and when this icon appears it cuts
> it to about 4 levels.

This typically means broken crap that reacts to brightness *change* events
as if they were keypresses.  Thinkpad-acpi doesn't issue those events by
default exactly for that reason, but some distros insist in breaking things.
IMMV.  I have no idea what exactly happens when ACPI video is active, but it
is likely that it can be subject to the same problem.  You can even get it
broken three times over, by forcing both thinkpad-acpi AND acpi-video to
issue the events, and react to both events by messing with the display

  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh