Keyboard backlight doesn't light up after latest updates

[mkudro]

Does anyone experiencing the same? It was working just fine, whenever i touched key board would light up. After latest updates it stopped working. Just for kicks i loaded live cd and it works, so it's gotta be some update related issue (kernel?).
Strangest is that when i boot laptop keyboard lights up and just when it comes up to moment of mounting drives it's dies out...for good.
I did filed bug and it was assigned to kernel team, but something tells me that not much attention would be given to this issue.
Just wandering if i was only one with this...

[Evirus]

I experienced the same problem after a kernel upgrade. (Fedora 15 on a Sony VAIO Z VPCZ-1290X.)

I can restore the keyboard backlight by changing the value in /sys/devices/platform/sony-laptop/kbd_backlight from 0 to 1, but it changes back to zero after rebooting. The same thing happens to /sys/module/sony_laptop/parameters/kbd_backlight.

Everything works fine with the old kernel, 2.6.38.6-26.rc1.fc15.x86_64; it's just 2.6.40.4-5.fc15.x86_64 that doesn't work.

What is changing kbd_backlight to 0 with each reboot and how do I fix it so it starts with 1 instead?

Curiously, if I boot using the 2.6.38 kernel, kbd_backlight doesn't appear anywhere in the file system at all, and yet the backlight works normally, presumably controlled by the BIOS rather than the OS.

[mkudro]

haha ... i have same laptop . And unfortunately it's not just don't work with 2.6.40* kernels but anything beyond that too. i have compiled 3* kernel - same story. Just for sake of trying thigs i loaded live images of other distros running latest kernels, still no luck... i did submit a bug report, but it gets as much attention as Mongolian politics on European news channels

[Evirus]

I think I've got it.

Added file sony-laptop.conf with single line

options sony-laptop kbd_backlight=1

to /etc/modprobe.d/ and it seems to work fine now.

One of these days I'm going to learn how to walk.

[mkudro]

Thnx Evirus, worked like a charm.