More bits of, potentially useful information. After some more research, I tried the following commands which work for some people (through ssh):

For some people this brings the lights back on. For me it flashes the lights on the screen briefly, after which the lamps go off.

Also, "xrandr -d :0" produces the following:

Which shows the monitor and video card seem to have the right settings, aside from the lamps being off.

Just a note that compiling and installing kernel 2.6.39.1 doesn't solve the problem. Screen still goes blank when switching to KMS. Anybody knows if this bug gets reported directly to kernel development team - or there is some dedicated team for the Intel video driver somewhere?

Ran into the same problem with an HP laptop (posted a separate thread, link below), brightness is reduced to zero as soon as KMS kicks in at startup. All I had to do was restore it using the laptop's brightness function key. Don't know if this is considered a kernel bug, the same problem occurred when I compiled and tested with 2.6.39.3 and 3.0-rc7 kernels. In both cases I had to restore the brightness with the function key.

http://www.linuxquestions.org/questi...tartup-892419/

Hi,

Thanks for the reply. Unfortunately I can't do this on my laptop. Either the function keys for brightness are not recognised correctly by Linux, or it doesn't have any effect on the bug I'm experiencing.

I've stumbled in my searches over the following kernel bug, which is still open and looks like might be the cause of my woes. I will keep an eye on it and hope it will get fix sometime soon:

https://bugzilla.kernel.org/show_bug.cgi?id=31522

Just another note to say thank you for bringing this up again - it made me do some more googling - which finally resulted in at least a temporary fix.

First off, this bug seems to be specific to the Intel Mobile 4 Series graphics controller.

After trying various suggestions found online, adding the following to rc.local finally turns the screen lamps back on, while allowing me to use KMS and full resolution:

/sbin/setpci -s 00:02.0 F4.B=00

I have no idea what is meant to do, but it will serve me well until this kernel bug is squashed.

Glad to hear that. Funny thing is I searched and found your thread which helped me solve the same problem on this laptop here as it did not occur to me that this could be a backlight/brightness issue.
Since i had to blindly log on and startx (which was my workaround fix) I thought why not just edit inittab to start in X and skip the console logon altogether. When X came on it was barely visible, as described in one of your previous posts, so I look up the function keys in the laptop's manual, and find the combination Fn + F3 that turns up the light (Fn + F2 to dim).

You might want to try this kernel parameter, it fixed the black screen on bootup problem on my laptop,
I no longer have to use the Fn key to restore it

Thank you for your suggestion. I'm afraid on my laptop it doesn't seem to make any difference. And incidentally, the Fn+ key combinations for increasing and decreasing brightness on my machine don't seem to work.

The latest upgrade in current to 3.10.5 seems to have solved this issue on my laptop.
The "acpi_backlight=vendor" kernel parameter workaround is no longer needed.