[HP Pavilion 23] Brightness control doesn't work.

[Po-Hsu Lin]

CID: 201206-11410
The brightness control seems not working (although the brightness looks fine on this computer).
Neither installing the proprietary driver, kernel update nor disabling the ACPI backlight driver would solve this.

Steps:
1. Open System Settings
2. Select Brightness and Lock
3. Adjust the brightness with the scroll bar.

-or-
1. Press the brightness key on the keyboard.

Expected result:
The screen brightness should change.

Actual result:
The screen brightness doesn't change.
And if using the brightness key to control it, can only lower the brightness level of the indicator, but not raising it.
(The screen brightness remain the same.)

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.5.0-23-generic 3.5.0-23.35~precise1
ProcVersionSignature: Ubuntu 3.5.0-23.35~precise1-generic 3.5.7.2
Uname: Linux 3.5.0-23-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.25.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu 1563 F.... pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Card0.Amixer.info:
 Card hw:0 'PCH'/'HDA Intel PCH at 0xf7300000 irq 50'
   Mixer name : 'Realtek ALC269VC'
   Components : 'HDA:10ec0269,103c2aed,00100202'
   Controls : 21
   Simple ctrls : 10
Date: Tue Apr 16 00:53:44 2013
HibernationDevice: RESUME=UUID=a4bdae84-e104-4f58-97c3-e9760fa4fde7
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
IwConfig:
 eth0 no wireless extensions.

 lo no wireless extensions.
MachineType: Hewlett-Packard 23-1901
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 nouveaufb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-23-generic root=UUID=6f502a3e-870b-4939-b93b-e6692e39cb24 ro quiet splash initcall_debug vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.5.0-23-generic N/A
 linux-backports-modules-3.5.0-23-generic N/A
 linux-firmware 1.79.1
RfKill:

SourcePackage: linux
StagingDrivers: rts_pstor
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/04/2012
dmi.bios.vendor: AMI
dmi.bios.version: 8.07
dmi.board.name: 2AED
dmi.board.vendor: PEGATRON CORPORATION
dmi.board.version: 1.02
dmi.chassis.type: 3
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnAMI:bvr8.07:bd09/04/2012:svnHewlett-Packard:pn23-1901:pvr1.00:rvnPEGATRONCORPORATION:rn2AED:rvr1.02:cvnHewlett-Packard:ct3:cvr:
dmi.product.name: 23-1901
dmi.product.version: 1.00
dmi.sys.vendor: Hewlett-Packard

[Brad Figg (brad-figg)]

This change was made by a bot.

[Po-Hsu Lin (cypressyew)]

Same situation with 201208-11466 HP Pavilion Sleekbook 14
(but the brightness key sometimes does work)

[Po-Hsu Lin (cypressyew)]

Also affects 201209-11840 Dell XPS 13 (L322X)

Pressing the brightness key will change the brightness level indicator correctly, but brightness won't change.
Can't adjust brightness in System Settings too.

Failed with dim_brightness test in checkbox.

[Po-Hsu Lin (cypressyew)]

Please ignore comment #4, since the bug of that system is reported individually.

[James M. Leddy (jm-leddy)]

If the indicator changes it means that the keycode is being received correctly, and only the backlight is not working.

[James M. Leddy (jm-leddy)]

Does this problem also happen with the vga and noveau drivers?

[James M. Leddy (jm-leddy)]

Last comment from Keng-Yu

For this platform, there are two acpi nodes controlling the backlight from DSDT (_SB.PCI0.GFX0.LCD0 and DD02), current kernel code (drivers/acpi/video.c) can only support one ACPI BUS. It is suspected that kernel chose the non-working one.

[AceLan Kao (acelankao)]

I didn't have time to check this, but from what you described.
If there are 2 acpi_video in /sys/class/backlight, that means BIOS provides us 2 ACPI backlight devices.
But only one of them is the right one to adjust the brightness.

If the above guess is correct, then the 2 acpi backlight device should be
   /sys/class/backlight/acpi_video0
and
   /sys/class/backlight/acpi_video1
The working one should be acpi_video0, and acpi_video1 is the redundant one.
You can check it by echo value to the "brightness" file in those directory to figure out which one is working.

So, the problem is why gnome-setting-daemons choose to use acpi_video1 to adjust the brightness instead of acpi_video0.
More over, I think, in this case, g-s-d should try to adjust all acpi backlight devices if there are more than one device exists.
So, it's a BIOS issue or a g-s-d issue, not kernel.

[James M. Leddy (jm-leddy)]

Hi AceLan, this is private bug 1015475 if you want further detail.

[Po-Hsu Lin (cypressyew)]

Hello Acelan,
the system, HP Pavilion 23 (201206-11410), has only one acpi_video in /sys/class/backlight.

With nouveau driver, the brightness cannot be adjusted, but it works with the proprietary nVidia driver (version 319).

I will check HP Pavilion Sleekbook 14 (201208-11466) later.
Thanks.

[Po-Hsu Lin (cypressyew)]

Hello Acelan,

in reply to my comment #11, on 201208-11466,
there is only one acpi_video0 in /sys/class/backlight

but please ignore comment #3
I think 201208-11466 it's not affected by this.

[AceLan Kao (acelankao)]

Hi,

So, you mean the issue on machine 201206-11410 could be fixed by installing the proprietary driver.
And another machine 201208-11466 is not affected.
Then, looks like we can close this bug?

[penalvch (penalvch)]

Po-Hsu Lin, could you please provide the full computer model as noted on the sticker (ex. HP Pavilion 23-b119 All-in-One Desktop PC)? If unavailable, could you please provide your serial number and product number?

[Po-Hsu Lin (cypressyew)]

Hello AceLan,
yes, I verified this issue again with 12.04.2+ update (3.5.0-45) and 12.04.3 (3.8.0-29) on 201206-11410.

Brightness control works with the proprietary driver nvidia-319

And another machine 201208-11466 is not affected.