Backlight not working after resume

Backlight not working after resume

[Jean-Denis Girard]

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Hi list,

I have a Samsung q30 ultra-portable; ACPI video seems supported by
standard driver. After boot, backlight control works fine with the
dedicated laptop keys, but it no longer works after suspend / resume.
The laptop itself is still working: I can ssh, even X is working. I can
add an external screen and everything is OK, it's just the panel
backlight is off. I have tried several methods found on the Internet
(setpci, xrandr, sysfs) without luck.

I can do:
	echo x >/sys/class/backlight/acpi_video0/brightness
(x=0..7) to adjust brightness after boot. After resume, the command
works, but has no effect.

Video is:
~ Intel Corporation 82852/855GM Integrated Graphics Device

I'm using KMS since 2.6.31-rc something (it was not working before).
Before KMS, I used vbetool post to get my screen back on.

I filed a bug at freedesktop.org one month ago, there's more detail
there (acpidump, ...):
	http://bugs.freedesktop.org/show_bug.cgi?id=24201

Problem persists with kernel version is 2.6.32-rc5.

I can provide more info, and I'm willing to try corrections / patches to
solve this problem.


Thanks,
- --
Jean-Denis Girard

SysNux                  Systèmes  Linux  en Polynésie française
http://www.sysnux.pf/   Tél: +689 50 10 40 / GSM: +689 79 75 27
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