* Taylor Hedberg <tmhedberg@xxxxxxxxx> [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.
