Screen too bright (kernel 2.6.32.9-70 onwards)

[Mr Wolf]

Hi everyone!

I'm running Fedora 12 x86_64 Gnome and my video card is an ATI Radeon HD 3650. I'm using the open source video driver.

After updating the kernel to version 2.6.32.9-70, my LCD display has started being too bright, which makes it barely readable.
The problem is still there after upgrading to kernel 2.6.32.10-90. I've even tried to boot a live USB of Fedora 13 Alpha (desktop-x86_64-20100404.17.iso - downloaded from here (http://alt.fedoraproject.org/pub/alt/nightly-composes/desktop/) - which ships with kernel 2.6.33.1-19) but... same problem!
Now I have to use kernel 2.6.32.9-67, the latest one working perfectly.

Can anyone help me, please?

[BugRocks1]

By any chance under /proc/acpi is there any "brightness" file?

If so you may be able to define the brightness of your screen with:

echo -n 100 > /proc/acpi/video/VGA/LCD/brightness

Source:
http://www.wuglug.org.uk/tutorials/kernel/acpi

After reading this I must ask, have you tried the auto configuration button on your LCD first?
3.2. What devices are supported?

Suspend/resume for SATA devices is not working well yet. Jens Axboe has a
patch that will help for some users; see the [141]SATA driver section for
more.

Brightness controls for LCD panels is sometimes not controllable by ACPI;
often, the vendor uses some proprietary method, having the BIOS adjust
brightness directly when certain hotkeys are pressed. In this case you are
liable to see odd messages in your log like these:
kernel: atkbd.c: Unknown key pressed (translated set 2, code 0x85 on is
a0060/serio0).
kernel: atkbd.c: Use 'setkeycodes e005 <keycode>' to make it known.

Various ethernet cards have problems, but there are patches. See the
[142]Ethernet cards section for more.

ATI Radeon cards usually need help for suspend to RAM. See the [143]RadeonFB
patches section for more. [FIXME and see if this helps X].

See also the note above about supported hardware for information about other
video devices.
_____________

Source:
http://www.columbia.edu/~ariel/acpi/acpi_howto.txt

---------- Post added at 12:38 AM CDT ---------- Previous post was at 12:33 AM CDT ----------

acpidump can be used to trace the problem.

Dumping the good ACPI settings on the kernel that works and then dumping the bad ACPI ones and looking for the differences.

[Mr Wolf]

Thank you for your answer.

By any chance under /proc/acpi is there any "brightness" file?

Unfortunately there's no such file.

After reading this I must ask, have you tried the auto configuration button on your LCD first?

Yes, I have, but nothing has changed.

acpidump can be used to trace the problem.

Dumping the good ACPI settings on the kernel that works and then dumping the bad ACPI ones and looking for the differences.

I've tried to dump the ACPI settings with both kernel 2.6.32.9-67 and 2.6.32.9-70, but the output files are equal.

By the way, I'm not sure if saying that the screen is "too bright" is enough to describe the problem. Contrast is quite low, too.
I think a picture would explain the problem better. I'll try to take and post one.

[BugRocks1]

By the way, I'm not sure if saying that the screen is "too bright" is enough to describe the problem. Contrast is quite low, too.
I think a picture would explain the problem better. I'll try to take and post one.

Maybe the gamma got confused.

Checking your gamma values:
xgamma

$ xgamma
-> Red 1.000, Green 1.000, Blue 1.000

Setting a new gamma value:
xgamma -gamma 0.6

Source:
http://ubuntuforums.org/showthread.php?t=149539
http://www.normankoren.com/makingfineprints1A.html

---------- Post added at 02:02 AM CDT ---------- Previous post was at 02:00 AM CDT ----------

Also your video card may have settings if you use nvidia those are easy to set up, for ATI there is a lot of parameters.

[Mr Wolf]

Maybe the gamma got confused.


Source:
http://ubuntuforums.org/showthread.php?t=149539
http://www.normankoren.com/makingfineprints1A.html[COLOR="Silver"]

Now the screen is more readable, but colours aren't OK yet (e.g., the grey Gnome panels and menus look white).

[BugRocks1]

You could try:
xgamma -gamma 1.0

I was reading this:
http://www.linux.com/archive/feature/113936

So you may want to see if there is a gamma correction also on your monitor.

---------- Post added at 02:31 AM CDT ---------- Previous post was at 02:23 AM CDT ----------

Great page for testing your settings :)

http://www.lagom.nl/lcd-test/

Other settings like contrast and colors you can do in System -> Administration -> Display or type:

su -
system-config-display

For some reason mine is not working so I'm using the config utility from nvidia.

[Mr Wolf]

I've connected the screen cable to the second DVI port of my graphics card. As a result, the problem has gone! :eek:
Perhaps something was wrong with the first DVI port. Why it was having troubles only with some versions of the kernel is still a mystery. :confused:

Thanks for your help and sorry for the time I've made you loose.