Bug 56011

Summary:	Backlight controls not working properly on Lenovo Thinkpad Edge e14 (0578A21)
Product:	ACPI	Reporter:	Artem Savkov (artem.savkov)
Component:	Power-Video	Assignee:	Aaron Lu (aaron.lu)
Status:	CLOSED DUPLICATE
Severity:	normal	CC:	aaron.lu, dannybaumann, lenb, rjw
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	3.9.0-rc4-next-20130328	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	dmidecode output acpidump output disassembled DSDT Enhance _BQC quirk check

Description Artem Savkov 2013-03-31 10:33:59 UTC

_BQC seems to always return zero making backlight control to not work properly, i.e. only 2 lower brightness levels are available.

Problem showed up after a bunch of fixes in acpi/video.c:
994fa63c5b126df6e9f31ef4e09000e2e243234b "ACPI / video: Fix applying indexed initial brightness value."
2d4128a25206685aaccaf14220c8436b11c6dc01 "ACPI / video: Make logic a little easier to understand."
a89803df9c9b2d023227c48503066a728f1fed36 "ACPI / video: Fix brightness control initialization for some laptops."

With this commits reverted controls works fine but only because BQC get's disabled due to invalid value being returned on initial BQC call.

Comment 1 Artem Savkov 2013-03-31 10:34:17 UTC

Created attachment 96721 [details]
dmidecode output

Comment 2 Artem Savkov 2013-03-31 10:34:42 UTC

Created attachment 96731 [details]
acpidump output

Comment 3 Artem Savkov 2013-03-31 10:35:26 UTC

Created attachment 96741 [details]
disassembled DSDT

Comment 4 Aaron Lu 2013-03-31 12:33:30 UTC

Created attachment 96751 [details]
Enhance _BQC quirk check

Hi Artem,

Please test if this patch fixed the problem, thanks. Apply on top of the -next tree.

Comment 5 Artem Savkov 2013-03-31 13:01:55 UTC

Hi Aaron,

Yes, this patch works for me. BQC is disabled on init as intended.

Comment 6 Aaron Lu 2013-04-01 05:14:56 UTC

(In reply to comment #5)
> Hi Aaron,
> 
> Yes, this patch works for me. BQC is disabled on init as intended.

And does it work as expected afterwards?

Comment 7 Artem Savkov 2013-04-01 05:32:56 UTC

Yes it just uses backlight->curr so things are back to normal, i.e. both buttons and xbacklight work normally.

Comment 8 Aaron Lu 2013-04-03 03:16:35 UTC

Hi Artem,

I'll mark this bug as a duplicate of #42861, though they are not exactly the same, but they share something in common and can be solve in the same way.

And I just proposed an updated patch, it shouldn't affect you, but if you have time, please kindly give it a test, thanks.

*** This bug has been marked as a duplicate of bug 42861 ***