[arch-general] Display issues with Linux 3.1

Mauro Santos registo.mailling at gmail.com
Thu Nov 10 09:00:48 EST 2011

On 10-11-2011 06:45, Uli Armbruster wrote:
> * Taylor Hedberg<tmhedberg at gmail.com>  [10.11.2011 01:55]:
>> Since updating to Linux 3.1 yesterday, I've been having strange problems
>> with the display on my laptop. The first reboot after updating the
>> kernel went normally, but every subsequent boot since then has had
>> problems.
>> This is a Dell Latitude D620 laptop with the following graphics-related
>> lines in the lspci output:
>> 00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
>> 00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)
>> During boot, at the stage where it says "Waiting for UDev uevents to be
>> processed", the backlight normally blinks and the display mode changes,
>> presumably due to udev detecting my graphics hardware.
>> Since the kernel update, the backlight still blinks off momentarily, but
>> when it comes back on, the screen remains blank. Rather than seeing the
>> rest of the boot messages, the display is just black (but backlit). The
>> system still seems to boot like normal; I boot to the virtual console
>> rather than starting X automatically, and once the hard disk activity
>> stops after booting, I can blindly type my login credentials and issue
>> shell commands, though I still can't see any output.
>> Additionally, after the first reboot following the update (which did not
>> have the aforementioned display problems), I had issues with the display
>> backlight after starting X. If I shut the laptop lid, the backlight
>> usually shuts off, and comes back on when I reopen it. However, after
>> the kernel update, around 80% of the time, the backlight seemed to come
>> back on at about a third of its usual brightness. I had to close and
>> reopen it several times, and eventually it would come on at full power
>> like normal.
>> I managed to boot the system in single-user mode using the fallback
>> initcpio image (any other combination of boot options seemed to result
>> in the blank screen), and then downgraded the kernel back to 3.0.7.
>> After downgrading, all of these problems seem to have disappeared.
>> I've scanned through dmesg output and I don't really see anything out of
>> the ordinary. But I admit that I don't really know what I'm looking for.
>> Any thoughts or suggestions?
> I can confirm this behavior, however I'm not sure if it's software related. I have the impression that this happens here only if the laptop is cold (e.g. because I carried it around outside in the cold german autumn). But Taylor's describtion fits perfectly to the behavior I have, so maybe it really is caused by the kernel.
> I have a
> 01:00.0 VGA compatible controller: ATI Technologies Inc RV350 [Mobility Radeon 9600 M10]
> and use the radeon driver.

Works fine for me here after a few reboots/cold boot/hibernate. I'm 
using the radeon driver with:
01:00.0 VGA compatible controller: ATI Technologies Inc Mobility Radeon 
HD 2400

Mauro Santos

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