[ltp] ibm-acpi brightness problems on the X60

Henrique de Moraes Holschuh linux-thinkpad@linux-thinkpad.org
Thu, 8 Mar 2007 04:05:53 -0300

On Thu, 08 Mar 2007, Fredrik Wendt wrote:
> Using the key combinations it's clear that we actually have 8 different
> levels (on the eightth (8th) key hit, nothing happens), the proc-acpi
> file says there are 7 levels.

I am *always* interested in these reports! (I am the ibm-acpi maintainer),
so, unfortunately for you, I have noticed the thread and will now bug you to
find out about all of your ibm-acpi bugs ;-)

Ok, so, please boot the machine in single user mode, and don't let the
Xserver start.  Please remove the ACPI video module (rmmod video) *and*
ibm-acpi (rmmod ibm-acpi).  After all this, the thinkpad firmware is all that
is commanding the brightness buttons.

How many levels do you see when playing with the brightness keyboard
buttons, 7 or 8?

Now, please go into battery mode.  How many levels do you see?

Now please load ibm-acpi (modprobe ibm-acpi experimental=1).   Repeat the
tests, does anything change?

If you are feeling generous AND using 2.6.20, please load the video module
and repeat the tests, does anything change?

> I can dim the screen using "echo level 1 > /proc/acpi/ibm/brightness"
> but it only lowers the brightness to a fix level no matter if I echo
> level 1 or level 5 for instance. (It only takes one Fn+Home key stroke
> to get back to full brightness (no matter what "level" I echoed into the
> file).)

This is also interesting, and it shows a bug somewhere (might be in
ibm-acpi, or elsewhere).

Please boot the machine in single user mode, and don't let the Xserver
start.  Please remove the ACPI video module (rmmod video), but make sure
ibm-acpi is still loaded.

Does /proc/acpi/ibm/brightness work correctly, or does it still show the bug
you described?

> cat /proc/acpi/ibm/brightness always shows whatever was written/echoed
> to the file last - it's value doesn't change after hitting Fn+Home/End.

It should, as we ask the EC directly about the brightness level.  This is
bad.  Please send me the output of /proc/acpi/ibm/ecdump right before, and
right after you hit a Fn+Home/End that *did* change the display brightness,
but for which /proc/acpi/ibm/brightness doesn't show the correct value.
Does it happen only for level 7/8 or 0/1?  Or does it also happen on level

  "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