Bug 11557

Summary:	Controlling backlight on thinkpad x60
Product:	ACPI	Reporter:	Rafael J. Wysocki (rjw)
Component:	Power-Video	Assignee:	Zhang Rui (rui.zhang)
Status:	CLOSED DUPLICATE
Severity:	normal	CC:	acpi-bugzilla, mjg59-kernel, pavel
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.27-rc5	Subsystem:
Regression:	Yes	Bisected commit-id:

Description Rafael J. Wysocki 2008-09-12 12:04:15 UTC

Subject    : Controlling backlight on thinkpad x60
Submitter  : Pavel Machek <pavel@suse.cz>
Date       : 2008-09-08 15:10
References : http://marc.info/?l=linux-kernel&m=122088987319698&w=4
Handled-By : Matthew Garrett <mjg59@srcf.ucam.org>

This entry is being used for tracking a regression from 2.6.26.  Please don't
close it until the problem is fixed in the mainline.

Comment 1 Rafael J. Wysocki 2008-09-14 17:22:18 UTC

Apparently, this is not a regression from 2.6.26.

Comment 2 Rafael J. Wysocki 2008-09-14 17:22:23 UTC

On Sunday, 14 of September 2008, Pavel Machek wrote:
> On Sat 2008-09-13 16:13:30, Matthew Garrett wrote:
> > I don't think this is a regression. The correct way to drive this 
> > hardware has always been through the ACPI video driver. The fact that 
> > thinkpad-acpi would also attempt to drive it was a bug.
> 
> I'm pretty sure thinkpad-acpi is older then ACPI-video. So yes, I
> believe this is a regression, but it may be pretty old one.

Comment 3 Zhang Rui 2008-09-17 18:46:28 UTC

hmm, it's not unusual that a laptop has duplicate video devices.
but it's interesting that both of them can control the backlight.

Paval,
can you attach the acpidump output please?

Comment 4 Zhang Rui 2008-09-25 18:12:55 UTC

there are two problems here.
1. backlight control from thinkpad_acpi is not enabled by default any longer. this is why it's marked as a regression.
2. duplicate functional ACPI backlight devices on this platform. this should be fixed by thomas/matthew video patches which are in Andi's acpi test tree now.

1 should not be an issue any more if the new patches are applied. i.e. there should be one ACPI backlight device under /sys/class/backlight/, instead of the thinkpad one.
mark this as a duplicate of bug 11647.

*** This bug has been marked as a duplicate of bug 11647 ***