Bug 13826

Hi, Pavel
    Will you please attach the output of acpidump?
    From the description it seems that this is a regression. Will you please try to use the git-bisect to identify the commit which causes the regression?
    Thanks.

it seems that the backlight is controlled by thinkpad-acpi driver.

Paval and Tobias,
it would be good if you can attach the acpidump and dmesg of your laptop here.

Paval,
it would be great if you can confirm that the problem on your laptop is same.

Paval does not subscribe to kernel bugzilla?

Created attachment 22506 [details]
dmesg output of 2.6.31-rc4 on my IBM X41 Tablet (thinkpad_acpi loaded as module later, with option brightness_mode=2 in /etc/modprobe.d/thinkpad.conf to fix the backlight interaction)

Created attachment 22507 [details]
acpidump output on my IBM X41 Tablet

Confirmed to be a problem in thinkpad-acpi.

The patch is ready (it had been already reported, I will check if it already has a bugzilla entry when I get home).

Will submit the patch later today or early tomorrow, and attach it here.

On Monday 27 July 2009, Tobias Diedrich wrote:
> Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of recent regressions.
> > 
> > The following bug entry is on the current list of known regressions
> > from 2.6.30.  Please verify if it still should be listed and let me know
> > (either way).
> 
> Yes, this still applies to 2.6.31-rc4.
> If I  don't add brightness_mode=2 the backlight controls don't work
> properly.
> 
> > Bug-Entry   : http://bugzilla.kernel.org/show_bug.cgi?id=13826
> > Subject             : thinkpad boots with backlight low
> > Submitter   : Pavel Machek <pavel@ucw.cz>
> > Date                : 2009-07-15 15:13 (12 days old)
> > References  : http://marc.info/?l=linux-kernel&m=124756359126830&w=4
> > Handled-By  : Henrique de Moraes Holschuh <hmh@hmh.eng.br>

(In reply to comment #0)
> Subject    : 2.6.31-rc2: thinkpad boots with backlight low
> Submitter  : Pavel Machek <pavel@ucw.cz>
> Date       : 2009-07-15 15:13
> References : http://marc.info/?l=linux-kernel&m=124756359126830&w=4
> Handled-By : Henrique de Moraes Holschuh <hmh@hmh.eng.br>
> Notify-Also : Tobias Diedrich <ranma+kernel@tdiedrich.de>
> 
> This entry is being used for tracking a regression from 2.6.29.  Please don't
> close it until the problem is fixed in the mainline.

I recently bought an Acer Travelmate 4530 AMD Athlon 64 dual-core with ATI Radeon
HD3200 graphics on which I installed Debian/Sid. When using kernels 2.6.30 and 31
the backlight control doesn't work well.
Only occasionly there is /sys/class/backlight and /sys/devices/virtual/backlight/acpi_video, most times these dirs are empty.
Sometimes it boots with backlight very low, sometimes maximum.
When the mentioned dirs are empty there is no control of the backlight, otherwise
the control is buggy, too dark or to light.
When using linux-image-2.6.29 there's no problem with the backlight.

(In reply to comment #7)
> I recently bought an Acer Travelmate 4530 AMD Athlon 64 dual-core with ATI
> Radeon

What you describe is a separate problem, please report it as a standalone bug.

Created attachment 22568 [details]
Do not use ECNVRAM mode on Intel-based GPUs

Patch published, marking FIXED CODE_FIX...

Oops, reopening until it hits mainline...

Patches sent to mainline by Len Brown, waiting for Linus to merge...

merged in mainline, commit 59fe4fe34d7afdf63208124f313be9056feaa2f4.

Now, needs to go to 2.6.30 through -stable.

Accepted in -stable, waiting push...