[arch-general] Display issues with Linux 3.1

[hollunder at lavabit.com]

> 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'm rather sure this is a new intel driver bug, I have the exact same issue.
My laptops chipset is slightly newer:
00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960
Integrated Graphics Controller (primary) (rev 03)
00:02.1 Display controller: Intel Corporation Mobile GM965/GL960
Integrated Graphics Controller (secondary) (rev 03)

The backlight thing is a completely unrelated issue. I couldn't care less
about the backlight when all I get to see is a blank screen. Did someone
find/file a bug at kernel.org already?