Bug 10206

Created attachment 15190 [details]
acpidump output

Created attachment 15195 [details]
debug patch

Will you please try the debug patch and see whether the entry is created in /sys/class/backlight/? 
Thanks.

Now there are some problems about the fujitu-laptop platform driver. 
Please ignore the entry in /sys/class/backlight/fujitsu-laptop . 

After the debug patch in comment #2 is applied, please confirm whether the brightness can be changed by Sys I/F?
Thanks.

I tried the debug_patch and it is working¹. I get /sys/class/backlight/acpi_video0/ and brightness can be changed by writing to /sys/class/backlight/acpi_video0/brightness.

Thanks.

¹After suspend-to-RAM it does not work until the xserver ist restartet.

Thanks for the test.

According to the description it seems that the system can be resumed from suspend state. The only problem is that it is necessary to restart the xserver.

Will you please confirm whether the system can be resumed in console mode? (Add the boot option of "3")

Thanks.

  The _BQC object is required by current video driver.  But unfortuately the optional _BQC object doesn't exist in the laptop. So the video driver won't register backlight device, which causes that there is no entry in /sys/class/backlight/
   
   As pointed in comment #3, there are some problems about the fujitu-laptop platform driver. The driver will register backlight device even when the acpi device of "FUJ02B1" HID doesn't exist. It is incorrect.
   
   The remaining problem is that it doesn't work until the xserver is restarted.
   Please confirm whether the system can be resumed succefully in console mode?(Add the boot option of "3" to enter the console mode.)
   Thanks.

Yes, the system can resume from suspend-to-ram.

• If I suspend from within X (via kpowersave or /usr/sbin/pm-suspend), after resume the backlight is on and brightness-control does not work. After restarting the X-server brightness-control works.

• After suspend the consoles are dark and blank¹, regardless if X is running or not. This might be some other problem.

a) If X is running and I suspend from a console, after resume the console is dark and blank¹ and brightness-control does not work. After restarting X brightness-control does work.

b) If no X is running, and I suspend from a console, after resume the console is dark and blank¹ and brightness-control does not work. After starting X brightness-control does still not work.
__________
¹ “console is blank” means there are no characters on it and there is no visible difference to a powerless LCD. 

re: no backlight on resume from console mode.
Looks like this is an Intel GMA 900 machine.
So please try the latest upstream i915 driver ie. 2.6.25-rc5
which should be able to restore video even in console mode.

applied the list version of the patch in comment #3 to acpi tree.

ie. just this part:

-       if (device->cap._BCL && device->cap._BCM && device->cap._BQC && max_level > 0){
+       if (device->cap._BCL && device->cap._BCM && max_level > 0) {

I tried 2.6.25-rc5 with the BQC-patch and now the brightness-control works after suspend-to-ram on X and on consoles and consoles are no longer blank after resume.

Thanks.

thanks for testing!

shipped in linux-2.6.25-rc5-git4
closed.

Bug has been reintroduced in 2.6.25, with commit 797de7bdb253624c16144f40b72ec65d63cdcca2

Created attachment 16310 [details]
the updated patch

The attached it the updated patch.
Will you please try it and see whether it works for you?
Thanks.

Sorry for needing so long for testing.

I tried the patch with 2.6.25.4 and it's working.

Thanks.

The last patch is still not in 2.6.26.1. Why is this?

Now the commit is already in upstream kernel. But we have to wait for some time before it is in stable kernel.

>commit c2c789057f075022658b38b498755c29c1ba8055
>Author: Zhao Yakui <yakui.zhao@intel.com>
<Date:   Thu Jul 17 10:46:05 2008 +0800

    ACPI: Ignore _BQC object when registering backlight device
Thanks.

shipped in 2.6.27:

Author: Zhao Yakui <yakui.zhao@intel.com>  2008-07-16 22:46:05
Committer: Andi Kleen <ak@linux.intel.com>  2008-07-17 19:41:49
Parent: 4a5e3638b11978262ab76bbb2062e57fefaaedba (ACPI: stop complaints about interrupt link End Tags and blank IRQ descriptors)
Branches: master, remotes/origin/master
Follows: v2.6.26
Precedes: v2.6.27-rc1

    ACPI: Ignore _BQC object when registering backlight device

Created attachment 18346 [details]
patch vs 2.6.26.6 sent to stable@kernel.org

find the same bug in v2.6.30
is this patched in 2.6.30?