HP Pavilion dv6 + Ubuntu 11: cannot change screen brightness

[rainbowfish]

I am having a problem with the brightness control on my HP dv6-6195ca laptop. I've been fiddling with this for hours now to no avail.

The F2/F3 keys are recognized in Ubuntu 11.04 and I see the popup showing the brightness increasing and decreasing, but it has no effect on the screen.

I've looked around and a lot of threads suggest working with /proc/acpi/video/VGA/LCD/brightness, but I don't have a video directory under /proc/acpi.

/proc/acpi$ ls -l
total 0
dr-xr-xr-x 3 root root 0 2011-10-04 19:06 ac_adapter
dr-xr-xr-x 3 root root 0 2011-10-04 19:06 battery
dr-xr-xr-x 4 root root 0 2011-10-04 19:06 button
-r-------- 1 root root 0 2011-10-04 19:01 event
-rw-r--r-- 1 root root 0 2011-10-04 19:06 wakeup

lspci output:

$ lspci
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
00:01.0 PCI bridge: Intel Corporation 2nd Generation Core Processor Family PCI Express Root Port (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #2 (rev 05)
00:1b.0 Audio device: Intel Corporation 6 Series Chipset Family High Definition Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 1 (rev b5)
00:1c.1 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 2 (rev b5)
00:1c.2 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 3 (rev b5)
00:1c.3 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 4 (rev b5)
00:1d.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #1 (rev 05)
00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 6 Series Chipset Family 6 port SATA AHCI Controller (rev 05)
00:1f.3 SMBus: Intel Corporation 6 Series Chipset Family SMBus Controller (rev 05)
01:00.0 VGA compatible controller: ATI Technologies Inc Device 6740
07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06)
0d:00.0 Network controller: Intel Corporation Centrino Wireless-N 1030 (rev 34)
13:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5209 (rev 01)
19:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04)

It appears that everything is working in Ubuntu, but I suspect that the brightness setting is not being sent to the hardware. When I turn the brightness up and down, it is being registered:

Full brightness:

$ cat /sys/devices/virtual/backlight/acpi_video0/brightness
10
$ cat /sys/devices/virtual/backlight/acpi_video1/brightness
10

Lowest brightness:

$ cat /sys/devices/virtual/backlight/acpi_video0/brightness
0
$ cat /sys/devices/virtual/backlight/acpi_video1/brightness
0


Any suggestions?

[pepe999]

Hi,

What graphics card do you use?? There are two graphics cards and it has not been solved properly yet..

[rainbowfish]

AMD 2GB Radeon HD 6770M

[pepe999]

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rainbowfish wrote:

AMD 2GB Radeon HD 6770M

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I would take a look on Compiz. This app causes many graphical problems..