[HP Presario CQ61] changing brightness freezes computer with KMS

A likely candidate for this could be the powersave scripts. Can you please uninstall the pm-utils-powersave-policy package, and check if it still happens?

If so, please reinstall it again, and try this instead:

  sudo mv /usr/lib/pm-utils/power.d/95hdparm-apm /usr/lib/pm-utils/power.d/95hdparm-apm.orig

If it still happens, please move it back with

  sudo mv /usr/lib/pm-utils/power.d/95hdparm-apm.orig /usr/lib/pm-utils/power.d/95hdparm-apm

Right after you encounter such a freeze, can you please reboot and attach /var/log/kern.log?

BTW, in your private mail you mentioned that you also have problems with the Fn keys. These are unrelated, so can you please file a separate bug about this with "ubuntu-bug udev" and there describe which keys cause the hang? Please let me know about the bug number here, so that I can find it/respond quickly.

This is what I have done. Some steps might seem strange but is explained by me not having an internet connection on the laptop when these tests are conducted (I will get the internet access back again)

First test:
1. A clean installation from the CD (I had massive problem with my fn-button freeze and after one hard reboot, I could not log in without a freeze, no matter what I did. I had to re-install Ubuntu 9.10 and then install Ubuntu 10.04 again before it worked (just re-installing Ubuntu 10.04 did not worked - even if I formatted the disk))
2. Boot
3. Unplugg the power cable
4. The laptop freezes
5. Hard reboot
6. Save log file as kern_mint.log

Second test:
1. Remove the pm-ubilt-powersave-policy package (sudo apt-get remove pm-utils-powersave-policy)
2. Unplugg the power cable
3. The laptop freezes
4. Hard reboot
5. Save log file as kern_nopmutils.log

6. Re-install Ubuntu 10.04 from the CD (This is to get the pm-utils-powersave-policies package back). I formatted the / partition but not the /home partition (I have three partitions on my disk /, /home and swap)

Third test:
1. Boot
2. Rename file (sudo mv /usr/lib/pm-utils/power.d/95hdparm-apm /usr/lib/pm-utils/power.d/95hdparm-apm.orig)
3. Unplugg the power cable
4. The laptop freezes
5. Hard reboot
6. Save log file kern_renamefile.log

7. Rename back the file (sudo mv /usr/lib/pm-utils/power.d/95hdparm-apm.orig /usr/lib/pm-utils/power.d/95hdparm-apm)

As you can see, nothing of the suggested things solved the problem. I hope that the logs contain the information you need. Is there any other logs that I can take to help you?

Another side note? Why is there no submit field on the Add Comment box? It took me several attempts to get the comment added...

Martin,

I have now reported the bug for the freeze when using fn-buttons. Please see:
619397 Laptop freeze when changing brightness

When investigating this I ran across a separate bug that also causes a freeze but I believe it might be slightly different than this. I will let you know about the number for that one as well.

I have written a third bug report 619450 Re-installation needed after laptop hibernation. All of them causes my laptop to freeze and they are all three in some way related to the backlight. Could there be a common cause to these faults?

Hm, I'm afraid none of the three kernel logs contain any kind of oos or other error message. Seems it freezes so hard and fast that it doesn't have a chance of writing the logs any more.

The three things I mentioned (hdparm, pm-utils, and acpi-support) are the obvious candidates for stuff that happens if you remove the power cable. Here are some more things you can try. For those you'll need to do things in the boot menu, please see

  https://help.ubuntu.com/community/BootOptions#Change%20Boot%20Options%20Permanently%20On%20An%20Existing%20Installation

for how to get into the boot menu and how to specify options.

 (1) Please select the rescue mode, wait until you see the menu. Does pulling the power cable cause the freeze here? Do you see any screen output? If so, please make a photo with a digital camera and attach it.

 (2) Please append a kernel boot option "nomodeset", and boot. Does the problem occur now?

Oh, and finally, if you are in the desktop, can you please open a Terminal, enter "killall gnome-power-manager", and check if the problem still happens? (freeze with the brightness keys or the power cable)

This is the results for these tests:

Recovery mode
Blinking cursor half way down the screen - No menu or prompt appear.
Pulling the power cable
!! No freeze appear
Keyboard answer to input
On one occation it I got the same fault message under ctrl-alt-f7 as can be seen in #619450

nomodeset + graphical mode
Startup as normal
pull the cable
!! No freeze appear
the screen does dim down after a while and I get information about battery discharge

nomodeset + recovery mode
Startup as normal
In the menu I chose root in prompt
Pull the power cable
!! No freeze

killall gnome-power-manager
Pulling power cable
!! No freeze
The screen does not dim down after a while and no information that the charger has been disconnected.

I have done the same setup with the fn button freeze that I have experienced. See bug #619397 for results of that.

Ah, sso I think this bug and bug 619397 are actually duplicates. When you remove the power cable, then gnome-power-manager tries to adjust the screen brightness.

So this looks like a bug in the ATI kernel DRM driver. Do you get the freeze if you do this?

  echo 3 | sudo tee /sys/class/backlight/*/brightness

Please also give me the output of

  ls -l /sys/class/backlight/

for completeness.

The exact command that I issued:
echo 3 | sudo tee /sys/class/backlight/acpi_video0/brightness

The result of this command was a freeze this time as well (expected??).

The output of ls -l /sys/class/backlight/ is:
prompt> ls -l /sys/class/backlight/
total 0
lrwxrwxrwx 1 root root 0 2010-08-20 18:26 acpi_video0 -> ../../devices/virtual/backlight/acpi_video0
prompt>

I am not surprised if this would be a duplicate with bug 619397. I wrote them both as there is different use cases but they do indeed have the same symptom.

Yes, I expected this. So this is definitively a kernel bug, reassigning. As a workaround, you can use the "nomodeset" boot option for now.

Thanks for debugging! The kernel team will most likely have more questions/tests for you, though.

This bug reappeared on Ubuntu 10.10

Hi, I stumbled across this bug when looking for answers. I have the same laptop, and I just installed Linux Mint Debian Edition. I get all the same freezing as well.

I just tried installing the latest gnome-power-manager (2.32.0-2) and my system went into a freeze on boot.. I have a feeling that this is the source of the problem.