Bug 578504

Summary:	Kernel bisect for: Cannot dim display on laptop anymore
Product:	Gentoo Linux	Reporter:	lebkoungcity
Component:	[OLD] Core system	Assignee:	Gentoo Kernel Bug Wranglers and Kernel Maintainers <kernel>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	Normal
Version:	unspecified
Hardware:	x86
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---
Attachments:	bisect.log (piped from 'git bisect') output of 'git bisect log' emerge --info lspci -v (complete)

Description lebkoungcity 2016-03-29 11:18:48 UTC

Created attachment 429216 [details]
bisect.log (piped from 'git bisect')

Hello,

I have a trouble with adjusting the brightness of the display on my ThinkPad R40. Since updating the kernel last August (I think it was from 3.18.12 to 4.0.5 - both being gentoo-sources) I cannot dim the backlight anymore. The brightness can be switched to it's full level but it can't be dimmed afterwards. The only way to achieve this is to give the command that it should be dimmed and then reboot the machine or switch it to hibernation and recover it from there.

I have started this thread in which I was advised to bisect the kernel:
https://forums.gentoo.org/viewtopic-p-7898434.html

The result is this:

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146755923262037fc4c54abc28c04b1103f3cc51 is the first bad commit
commit 146755923262037fc4c54abc28c04b1103f3cc51
Author: Jay Lan <jlan@sgi.com>
Date: Mon Sep 29 15:36:57 2014 -0700

kdb: fix incorrect counts in KDB summary command output

The output of KDB 'summary' command should report MemTotal, MemFree
and Buffers output in kB. Current codes report in unit of pages.

A define of K(x) as
is defined in the code, but not used.

This patch would apply the define to convert the values to kB.
Please include me on Cc on replies. I do not subscribe to linux-kernel.

Signed-off-by: Jay Lan <jlan@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

:040000 040000 933e89763afe1823fa7ed3980486d396a6a0721b c0993777db35918f12790d5a5662320bb0814a07 M kernel

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I hope that this is a valide result.

I attach the complete logs incl. emerge --info and I'd be happy to provide more info!

Comment 1 lebkoungcity 2016-03-29 11:20:09 UTC

Created attachment 429218 [details]
output of 'git bisect log'

Comment 2 lebkoungcity 2016-03-29 11:20:57 UTC

Created attachment 429220 [details]
emerge --info

Comment 3 lebkoungcity 2016-03-29 11:22:37 UTC

Created attachment 429222 [details]
lspci -v (complete)

Comment 4 Mike Pagano gentoo-dev

2018-03-05 17:54:54 UTC

Is this still an issue with later kernels?

Comment 5 lebkoungcity 2018-03-11 20:48:35 UTC

No, it works again with recent kernels.

Thanks for asking!