Bug 78011

Summary:	laptop panel backlight is dropped to 0 when external VGA display is connected
Product:	Drivers	Reporter:	Anton Gubarkov (anton.gubarkov)
Component:	Video(DRI - Intel)	Assignee:	Jesse Barnes (jbarnes)
Status:	RESOLVED CODE_FIX
Severity:	normal	CC:	intel-gfx-bugs
Priority:	P3
Hardware:	x86-64
OS:	Linux
See Also:	https://bugzilla.kernel.org/show_bug.cgi?id=77091
Kernel Version:	3.15.0	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	log of external monitor connection with drm.debug=0x4 and module backlight +fpt

Description Anton Gubarkov 2014-06-16 06:42:24 UTC

Actual behavior:
Every time I connect an external display, my internal panel brightness is
brought to 0. 

Expected behavior:
The internal panel brightness doesn't change when there is a desktop displayed
on it.

Comment 1 Anton Gubarkov 2014-06-16 06:44:32 UTC

Created attachment 139871 [details]
log of external monitor connection with drm.debug=0x4 and module backlight +fpt

Comment 2 Jani Nikula 2014-06-16 09:09:16 UTC

Please attach dmesg from early boot with drm.debug=0xe module parameter set, exhibiting the problem.

Is this a regression? Did this work in the past?

Comment 3 Hans de Goede 2014-06-16 09:30:34 UTC

This seems to be the same issue as reported here:
https://bugzilla.redhat.com/show_bug.cgi?id=1012674

Which is actually an issue in xf86-video-intel, which has been fixed in the recent 2.99.912 release, please give that version a try.

Comment 4 Anton Gubarkov 2014-06-16 10:12:05 UTC

(In reply to Hans de Goede from comment #3)
> This seems to be the same issue as reported here:
> https://bugzilla.redhat.com/show_bug.cgi?id=1012674
> 
> Which is actually an issue in xf86-video-intel, which has been fixed in the
> recent 2.99.912 release, please give that version a try.

Upgrade of xf86-video-intel package solved my problem indeed. Thank you very much.

Comment 5 Jani Nikula 2014-06-16 12:28:51 UTC

Anton, thanks for the report and testing.

Hans, thanks for your continued help in nailing down the backlight bugs!