My laptop screen is (almost) black while my secondary screen is fine. I believe it to be backlight / brightness related.
- it starts when I start the laptop
- system loads and works fine, just screen has problems
- I can see the screen though very faintly / dimly - it's hard to see anything which ain't very white e.g. starting screen has big Thinkpad logo in white, large font - I can see it, though very dimly
- second screen works very well
- using acpi setting as prescribed there for Thinkpads didn't help
- I can see an entry in
/sys/class/backlight/and it changes when I press hotkeys for brightness (current backlight power for instance goes up or down)
acpi-offdidn't helpm neither did
Laptop is Thinkpad Edge with glossy screen. 4 processors, 2 cores, exemplary CPU data from
cat /proc/cpuinfo reports Genuine Intel i5 (M 480 @ 2.67GHz).
OS is Ubuntu Lucid, 10.04 LTS, 64-bit, with Linux generic kernel (2.6.32-44) and GNOME 2.32.2 (though I doubt there lies the problem).
$ lspci | grep VGA 01:00.0 VGA compatible controller: ATI Technologies Inc M92 [Mobility Radeon HD 4500 Series] $ lshw -C display *-display description: VGA compatible controller product: M92 [Mobility Radeon HD 4500 Series] vendor: ATI Technologies Inc physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 32 bits clock: 33MHz capabilities: pm pciexpress msi bus_master cap_list rom configuration: driver=radeon latency=0 resources: irq:33 memory:c0000000-dfffffff(prefetchable) ioport:2000(size=256) memory:f0300000-f030ffff memory:f0320000-f033ffff(prefetchable)
I was NOT running any proprietary drivers, just checked with "Hardware drivers". There is one for ATI that is suggested there, though I didn't need it so far.
UPDATE: changing the driver to proprietary one (ATI/AMD FGLRX) didn't help.
Tried and failed
This is NOT a blank-screen problem, at least it isn't following official Ubuntu black-screen diagnostics - I can see my screen, though barely.
What I will try next: - check last updates I've made - IIRC I am running on nomodeset already, but will verify this
Any ideas how to proceed best? What is most probable cause?