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Created attachment 517198 [details]
Xorg.0.log

Description of problem:

changing resolution sets minimal brightness on the laptop display (external monitor is always fine).

I've also found out that enabling disabling external displays leads to same result (minimal brightness on the laptop display)

Workaround: return back brightness after any resolution manipulation by using hardware keys or other ...

Version-Release number of selected component (if applicable):

xorg-x11-drv-intel-2.15.0-2.el6.x86_64
xorg-x11-server-Xorg-1.10.3-3.el6.x86_64
xorg-x11-server-utils-7.5-5.1.el6.x86_64
kernel-2.6.32-178.el6.x86_64


How reproducible:

obtain t400 with mentioned versions of software

Steps to Reproduce:
1. switch resolution or enable / disable external display

  
Actual results:

minimal brightness on the laptop display (if any)

Expected results:

brightness should stay on the same level as before changing resolution

Additional info:

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

Comment on attachment 517198 [details]
Xorg.0.log

not sure if there is anything useful

Move to 6.2.

I can reproduce this on a T400, but not on a T500.  Curious.

Actually, I only tested the T500 with an external display attached, and in that configuration the T400 behaves sanely as well.  Seems to only happen with only the LVDS lit.

I'm no longer able to reproduce this with kernel-2.6.32-202.  Reporter?

Hello Adam, I can't use newer kernel as Bug 741192 is blocking me. If you were able to reproduce this issue before and now it's fine then it's probably CURRENT RELEASE.

I'll reopen bug in case that I'll hit this problem again on newer kernel.

I was able to reproduce the problem on my T500 - happened only to laptop lid. 
I can confirm it's fixed in xorg-x11-drv-intel-2.16.0-1.el6 and kernel-2.6.32-202.el6.