[gutsy] Screen brightness works only at certain values.

[Michael Lustfield]

Binary package hint: gnome-power-manager

How to reproduce:
Open gnome-power-manager
Change display brightness for either battery or AC power

Results
When I set the percentage to anything other than the following values, the screen is nearly entirely black.
%'s that work: 22-29, 46-54, 72-76, 97-100

This was happening with no additional software installed.

I have a Gateway M285-E Tablet PC if it helps any.

lspci : 01:00.0 VGA compatible controller: ATI Technologies Inc Radeon Mobility X1400

[Michael Lustfield (michaellustfield)]

I assume this has something to do with the kernel.
This bug is still an issue with the last two kernel updates.

[otdave (otdave)]

My screen only works on 100% brightness. Anything else results in black screen. Gateway MP8708 laptop.

[otdave (otdave)]

"My screen only works on 100% brightness. Anything else results in black screen. Gateway MP8708 laptop."

I didn't try the other settings in my original post. I have exactly the same problem as Micheal Lustfield. Screen works at 97-100%, 72-76% etc. I have an Intel AGM 950 vid.

[horizontaleight (mbyoung)]

I can confirm this issue to be present on my Gateway NX560x with the Intel 945 graphics chipset. Others have also seen this problem as per <a href="http://ubuntuforums.org/showthread.php?t=580535">this thread</a>. My display works at certain percentage ranges as noted in the first post. Any insight into this would be greatly appreciated as this was not an issue in Feisty.

[Matthew Dutton (matthewrdutton)]

I'm also having this problem with a Gateway MP8709 with Intel 945 chipset.

This bug looks related/duplicate of:
https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/121833

Seems as though there are 8-9 discrete backlight levels listed in /proc/acpi/video/VGA/LCD/brightness:
    levels: 100 37 12 25 37 50 62 75 87 100
    current: 0
but whatever is handling the ACPI brightness events is jumping in steps of 5%, missing 12, 37, 62 and 87.

The other bug referenced mentions that echo'ing an invalid value to /proc/.../brightness will error/fail but /sys/class/backlight/XXX/brightness will accept the bad value and essentially turn the backlight off.

[Matthew Dutton (matthewrdutton)]

See https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/121833 for an ugly hack for the problem

[horizontaleight (mbyoung)]

Hello,

I haven't checked my email in a bit and I just saw your bug fix for
the HAL issue in Gutsy. I wanted to thank you for responding. I am
going to try the fix tonight when I get home from work and see if it
can correct my issues. Thanks again,

-Michael

On Nov 13, 2007 4:01 AM, MRDutton <email address hidden> wrote:
> See https://bugs.launchpad.net/ubuntu/+source/gnome-power-
> manager/+bug/121833 for an ugly hack for the problem
>
>
> --
> [gutsy] Screen brightness works only at certain values.
> https://bugs.launchpad.net/bugs/149547
> You received this bug notification because you are a direct subscriber
> of the bug.
>

[Henrik Nilsen Omma (henrik)]

This bug was nominated for Gutsy but does currently not qualify for a 7.10 stable release update (SRU) and the nomination is therefore declined.
According the the SRU policy, the fix should already be deployed and tested in the current development version before an update to the stable releases will be considered. With 7.10 now released, that policy applies to this bug. See: https://wiki.ubuntu.com/StableReleaseUpdates .
The bug is not being closed as work will continue on fixing it for the next release, Hardy Heron (8.04). If the state of this bug should change such that it qualifies for the SRU process, please contact the person who originally declined it and ask them to re-evaluate it. To help improve the state of this bug see: https://wiki.ubuntu.com/Bugs/HowToTriage .

[sen123 (senthil-debian)]

senthil@curie:~$ sudo dmidecode -s system-manufacturer
Gateway
senthil@curie:~$ sudo dmidecode -s system-product-name
MX6917J
senthil@curie:~$ sudo dmidecode -s system-version
3402689R

Brightness is either 0 or 100, no intermediate values. BIOS graphic that pops up during changing the brightness with the hot keys is okay, does not garble anything.

Rest of the hot keys for Wireless, Volume, Caps Lock/Num Lock etc work fine. Bluetooth does not work though.

Thanks,

Senthil

[Michael Lustfield (michaellustfield)]

My problems have been solved. If anybody else experiences this problem, feel free to reopen this bug.