Bug#651741: gnome-power-manager: display backlight brightness has no effect on Sony Vaio VPCYA1V9E
Kalle Olavi Niemitalo
kon at iki.fi
Sun Dec 11 20:14:14 UTC 2011
Package: gnome-power-manager
Version: 3.0.2-3
Severity: normal
On a Sony Vaio VPCYA1V9E laptop, if I press Fn+F5 or Fn+F6, then
gnome-power-manager attempts to change the brightness of the
display backlight, and shows a window as if it had worked.
However, the brightness does not change. Likewise, if I change
the brightness via System Settings -> Screen, then the slider
does move, but it has no effect.
Linux 3.1.0 detects two backlight devices:
% ls -l /sys/class/backlight
total 0
lrwxrwxrwx 1 root root 0 Dec 11 20:10 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
lrwxrwxrwx 1 root root 0 Dec 11 20:21 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
% cat /sys/class/backlight/acpi_video0/max_brightness
8
% cat /sys/class/backlight/acpi_video0/type
firmware
% cat /sys/class/backlight/intel_backlight/max_brightness
4882
% cat /sys/class/backlight/intel_backlight/type
raw
Of these, only intel_backlight actually affects the screen of the
laptop; acpi_video0/brightness can be changed (by root) but does
not seem to affect anything. (I haven't tried with an external
display.) However, /usr/sbin/gnome-power-backlight-helper always
chooses acpi_video0 and ignores intel_backlight. It has a
built-in list of backlight devices that it tries to open;
acpi_video0 is on this list but intel_backlight is not.
Because it succeeds in opening acpi_video0, it does not read the
/sys/class/backlight directory to see what other devices exist.
GNOME 3.0 source code for selecting the backlight device:
http://git.gnome.org/browse/gnome-power-manager/tree/src/gpm-backlight-helper.c?h=gnome-3-0#n52
In GNOME 3.2, the code has been moved to gnome-settings-daemon,
but still does not recognize intel_backlight:
http://git.gnome.org/browse/gnome-settings-daemon/tree/plugins/power/gsd-backlight-helper.c?h=gnome-3-2#n49
It would be best if backlight control worked correctly with the
default settings. It seems the easiest way to achieve that is to
add "intel_backlight" to the list in {gpm,gsd}-backlight-helper.c,
somewhere above "acpi_video0" so that it takes precedence.
Alternatively, Linux could perhaps be made to entirely omit the
nonfunctional acpi_video0 backlight device and thereby cause
gnome-power-backlight-helper to read the directory and find
intel_backlight.
The acpi_backlight=vendor kernel option seems like a step in the
right direction, as it does make the
/sys/class/backlight/acpi_video0 directory disappear. However,
it also makes /sys/class/backlight/sony appear instead, and
"sony" is on the list in gnome-power-backlight-helper, which
therefore still does not read the directory. Unfortunately,
backlight control via the sony directory does not work either;
both brightness and actual_brightness are constantly -1 there.
If I use acpi_backlight=vendor and unload the sony-laptop module,
then the sony directory disappears too,
gnome-power-backlight-helper opens intel_backlight, and I can
finally change the brightness via the screen settings dialog box!
That solution is still not satisfactory though, because Linux
does not recognize the Fn+F5 and Fn+F6 key combinations without
the sony-laptop module.
The package-specific info below is incomplete because the
bug-reporting script tried to use HAL and I don't have that
installed. However, dmidecode shows:
# dmidecode 2.11
SMBIOS 2.6 present.
17 structures occupying 853 bytes.
Table at 0x000EA490.
Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
Vendor: INSYDE
Version: R0070Z6
Release Date: 11/02/2010
ROM Size: 2048 kB
Characteristics:
PCI is supported
PNP is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
EDD is supported
8042 keyboard services are supported (int 9h)
CGA/mono video services are supported (int 10h)
ACPI is supported
USB legacy is supported
Smart battery is supported
BIOS boot specification is supported
Function key-initiated network boot is supported
Targeted content distribution is supported
BIOS Revision: 0.70
Firmware Revision: 0.70
Handle 0x0001, DMI type 1, 27 bytes
System Information
Manufacturer: Sony Corporation
Product Name: VPCYA1V9E
Version: C9006WUT
Serial Number: (removed from bug report)
UUID: (removed from bug report)
Wake-up Type: Power Switch
SKU Number: N/A
Family: VAIO
Handle 0x0002, DMI type 2, 16 bytes
Base Board Information
Manufacturer: Sony Corporation
Product Name: VAIO
Version: N/A
Serial Number: C9006WUT
Asset Tag: N/A
Features:
Board is a hosting board
Location In Chassis: Base Board Chassis Location
Chassis Handle: 0x0003
Type: Motherboard
Contained Object Handles: 0
(handles 0x0003 to 0x0010 removed from bug report)
-- Package-specific info:
Distro version: wheezy/sid
Kernel version: 3.1.0-1-amd64
g-p-m version: 3.0.2
HAL version: System manufacturer: missing
System version: missing
System product: missing
AC adapter present: no
Battery present: no
Laptop panel present: no
CPU scaling present: no
Battery Information:
UPower data:
Device: /org/freedesktop/UPower/devices/line_power_ADP1
native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:0c/PNP0C09:00/ACPI0003:00/power_supply/ADP1
power supply: yes
updated: Sun Dec 11 20:10:53 2011 (1106 seconds ago)
has history: no
has statistics: no
line-power
online: no
Device: /org/freedesktop/UPower/devices/battery_BAT0
native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:0c/PNP0C09:00/PNP0C0A:00/power_supply/BAT0
vendor: Sony Corp.
model: VGP-BPS21B
serial: (removed from bug report)
power supply: yes
updated: Sun Dec 11 20:29:02 2011 (17 seconds ago)
has history: yes
has statistics: yes
battery
present: yes
rechargeable: yes
state: discharging
energy: 16.03 Wh
energy-empty: 0 Wh
energy-full: 40.56 Wh
energy-full-design: 41.04 Wh
energy-rate: 13.621 W
voltage: 10.768 V
time to empty: 1.2 hours
percentage: 39.5217%
capacity: 98.8304%
technology: lithium-ion
History (charge):
1323628142 39.522 discharging
1323628112 39.793 discharging
1323628082 40.089 discharging
1323628052 40.360 discharging
History (rate):
1323628142 13.621 discharging
1323628112 13.518 discharging
1323628082 13.499 discharging
1323628052 13.311 discharging
Daemon:
daemon-version: 0.9.14
can-suspend: yes
can-hibernate yes
on-battery: yes
on-low-battery: no
lid-is-closed: no
lid-is-present: yes
is-docked: no
GNOME Power Manager Process Information:
HAL Process Information:
-- System Information:
Debian Release: wheezy/sid
APT prefers testing
APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Kernel: Linux 3.1.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=fi_FI.utf8, LC_CTYPE=fi_FI.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages gnome-power-manager depends on:
ii consolekit 0.4.5-1
ii dbus-x11 1.4.16-1
ii dconf-gsettings-backend [gsettings-backend] 0.7.5-3
ii gnome-screensaver 3.0.1-3
ii gnome-settings-daemon 3.0.3-3
ii libc6 2.13-21
ii libcairo2 1.10.2-6.1
ii libcanberra-gtk3-0 0.28-3
ii libcanberra0 0.28-3
ii libglib2.0-0 2.30.2-4
ii libgnome-keyring0 3.2.0-3
ii libgtk-3-0 3.0.12-2
ii libnotify4 0.7.4-1
ii libpango1.0-0 1.29.4-2
ii libupower-glib1 0.9.14-3
ii libx11-6 2:1.4.4-4
ii libxext6 2:1.3.0-3
ii libxrandr2 2:1.3.2-2
ii notification-daemon 0.7.3-1
ii upower 0.9.14-3
Versions of packages gnome-power-manager recommends:
ii udisks 1.0.4-2
Versions of packages gnome-power-manager suggests:
ii policykit-1 0.102-2
-- no debconf information
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