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jiyunatori

Member

Registered: 2008-07-04

Posts: 54

[solved] thinkpad backlight/brightness problems

Hi there.

Since an update this morning, I have major troubles handling the brightness of my thinkpad X40.

resuming from pm-suspend lead to a black screen. actually, it is not exactly black for I can guess my wallpaper. It's like the image is displayed but the backlight is turned off.

bash-3.2# grep think /var/log/Xorg.0.log
(II) intel(0): found backlight control method /sys/class/backlight/thinkpad_screen
(EE) intel(0): write to /sys/class/backlight/thinkpad_screen/brightness for backlight control failed: Invalid argument

and in dmesg, I find this several times

thinkpad_acpi: CMOS NVRAM (0) and EC (1) do not agree on display brightness level

also, sometimes cat /proc/acpi/ibm/brightness answers "unreadable", but I fail to reproduce this systematically.

more informations on my system :

bash-3.2# uname -a
Linux aleph 2.6.25-ARCH #1 SMP PREEMPT Thu Jul 3 20:29:23 CEST 2008 i686 Intel(R) Pentium(R) M processor 1200MHz GenuineIntel GNU/Linux

bash-3.2# cat /proc/acpi/ibm/driver 
driver:        ThinkPad ACPI Extras
version:    0.19

I'm a bit lost here. In the meantime, I'm going to downgrade my kernel, to see if it solves the problem.

Last edited by jiyunatori (2008-07-15 20:16:22)

bbs

Member

From: MA

Registered: 2008-07-04

Posts: 47

Re: [solved] thinkpad backlight/brightness problems

on a first glance this appears to me that THINKPAD_EC -- a modules for doing things on thinkpads like extras hdaps etc... is interfereing with the NVRAM module which handles some of the same thinkpad extras in a different fashion -- could you post your kernel configuration please so i can have a look? -- I would also recommend another kernel for thinkpad machines

---

(quaqmire talking about a dude getting his tubes tied)
sex kinda looses its appeal without the potency -- its like a cobra without the venom -- i mean what do you have then....?  -- a belt?

bbs

Member

From: MA

Registered: 2008-07-04

Posts: 47

Re: [solved] thinkpad backlight/brightness problems

thinking further on this -- have you tried *AFTER* a pm-suspend to do CTRL-ALT-F1 to see if a tty will kick the lamp back on? -- or cycle it and see what happens?  -- let me know --

---

(quaqmire talking about a dude getting his tubes tied)
sex kinda looses its appeal without the potency -- its like a cobra without the venom -- i mean what do you have then....?  -- a belt?

jiyunatori

Member

Registered: 2008-07-04

Posts: 54

Re: [solved] thinkpad backlight/brightness problems

Hi there. first of all, thanks for your interest in my problem.

I think I've just solved it - or at least partly !

I found this discussion : http://www.nabble.com/display-with-back … 78474.html

I tried the first solution adding acpi_sleep=s3_bios on grub's kernel line.

and it works !

in the meantime, my problem got even more complex : the /proc/acpi/ibm/brightness file had disappeared. but now I added this option, it is back again.

I still get this "CMOS NVRAM and EC" error, but it seems to be fixable. It looks like when I boot up, cat /proc/acpi/ibm/brightness will answer me "unreadable", and I have the error in the logs. But then, all I have to do is playing with the brightness control a bit so both levels (CMOS and EC ?) are the same, and suddenly /proc/acpi/ibm/brightness gives me meaningful informations. then, I can change brightness either with the controls or by doing "echo level X > /cat/proc/acpi/brightness". Both will work, and brightness data will keep up.