Neither Brightness Applet Nor Fn Keys Work

[kaoskorruption]

Neither my brightness applet nor my Fn keys work to adjust the brightness. The applet just says "cannot get laptop panel brightness."

This is a Gateway T-6836.

Any ideas?

[ibuclaw]

does the following file exist?

 test -f /sys/devices/virtual/backlight/acpi_video0/brightness && echo YES || echo NO

If is does, try this:

echo 5 | sudo tee /sys/devices/virtual/backlight/acpi_video0/brightness

And see if the screen brightness changes

Regards
Iain

[kaoskorruption]

And what if it doesn't?

[ibuclaw]

It may appear that it isn't a supported feature with your motheboard.

Can you run this:

sudo lshw | head -n 30

And just paste the output of it on the forums so I can get a good idea of what motherboard/bios you are running with.

Regards
Iain

[cherok]

I've got the same problem.

I ran this code

 test -f /sys/devices/virtual/backlight/acpi_video0/brightness && echo YES || echo NO

... received a "NO" so I ran the the next one that you provided.

 description: Notebook
    product: HP Pavilion dv2000 (GM040UA#ABL)
    vendor: Hewlett-Packard
    version: F.34
    serial: 2CE7300NJP
    width: 32 bits
    capabilities: smbios-2.4 dmi-2.4 smp-1.4 smp
    configuration: administrator_password=enabled boot=oem-specific chassis=notebook cpus=1 frontpanel_password=unknown keyboard_password=unknown power-on_password=disabled uuid=E1062260-3BA4-11DC-B489-9520D860C330
  *-core
       description: Motherboard
       product: 30B5
       vendor: Wistron
       physical id: 0
       version: 62.57
     *-firmware
          description: BIOS
          vendor: Hewlett-Packard
          physical id: 0
          version: F.34 (06/02/2007)
          size: 96KiB
          capacity: 960KiB
          capabilities: isa pci pcmcia pnp apm upgrade shadowing escd cdboot acpi usb agp biosbootspecification
     *-cpu
          description: CPU
          product: AMD Athlon(tm) 64 X2
          vendor: Advanced Micro Devices [AMD]
          physical id: 4
          bus info: cpu@0
          version: 15.8.1

Thanks, any help would be great. I'm on a DV 2000 HP Pavilion, more specifically a DV2404ca

[kaoskorruption]

phantom                   
    description: Portable Computer
    product: T-6836
    vendor: Gateway
    version: 89.24
    serial: N1B86 T10 34697
    width: 32 bits
    capabilities: smbios-2.4 dmi-2.4 smp-1.4 smp
    configuration: administrator_password=disabled boot=oem-specific chassis=portable cpus=1 frontpanel_password=unknown keyboard_password=unknown power-on_password=disabled uuid=54726974-6F6E-2D2D-2D2D-0003254C3E47
  *-core
       description: Motherboard
       vendor: Gateway
       physical id: 0
       version: Rev1.89.24
       serial: V86JM0040709KF401X
     *-firmware
          description: BIOS
          vendor: Gateway
          physical id: 0
          version: 89.24 (05/22/2008)
          size: 105KiB
          capacity: 960KiB
          capabilities: isa pci pcmcia pnp upgrade shadowing escd cdboot acpi usb agp biosbootspecification
     *-cpu
          description: CPU
          product: Intel(R) Core(TM)2 Duo CPU     T5750  @ 2.00GHz
          vendor: Intel Corp.
          physical id: 4
          bus info: cpu@0
          version: 6.15.13

There's mine.

[solariz]

Same problem here on my Samsung X65, grmpf I need the laptop next week outside the office so I have now to install windows to use it ;(
It is so damn dark without brightness regulation as ssoon as there is any aylight I cant see anything on the display. I tried everything related to this topic in this forum but nothing solved the problem

 sudo lshw | head -n 30
PCI (sysfs)  
solariz-laptop            
    description: Notebook
    product: SX65S
    vendor: SAMSUNG ELECTRONICS CO., LTD.
    version: 05AF
    serial: 928Z93BP900023
    width: 32 bits
    capabilities: smbios-2.4 dmi-2.4 smp-1.4 smp
    configuration: administrator_password=disabled boot=oem-specific chassis=notebook cpus=1 frontpanel_password=unknown keyboard_password=unknown power-on_password=disabled uuid=A0742550-DB1D-B211-8000-D66D6926514D
  *-core
       description: Motherboard
       product: SX65S
       vendor: SAMSUNG ELECTRONICS CO., LTD.
       physical id: 0
       serial: 123490EN400015
     *-firmware
          description: BIOS
          vendor: Phoenix Technologies LTD
          physical id: 0
          version: 06AF (12/04/2007)
          size: 111KiB
          capabilities: isa pci pcmcia pnp upgrade shadowing escd cdboot acpi usb agp biosbootspecification
     *-cpu
          description: CPU
          product: Intel(R) Core(TM)2 Duo CPU     T7500  @ 2.20GHz
          vendor: Intel Corp.
          physical id: 4
          bus info: cpu@0
          version: 6.15.10
          slot: U2E1

One thing I noticed is that if i Press Fn UP/DOWN this only works during boot or if I manually shutdown GDM. So as soon as GDM is active I cant regulate the brigtness anymore.
Currently to regulate I have to /etc/init.d/gdm stop <regulate using Fn Keys> start gdm


grmpf

[DerSkw]

I have exactly the same problem with my Samsung x65!
But I think it is a problem of the NVidia driver because brightness control works with "nv" !

[J-Morris]

I am having the exact same problem as everyone else here. I am running an HP lap top just like the cool cat above. I would like to see a solution.

[Leviathan2k]

Similar problem for me. Running fresh-installed Ubuntu 8.10rc1 on a Samsung R700. Everything worked fine with the Live CD and also with the installed version, until I installed nvidia drivers. Since then, I cannot activate my second monitor and I cannot change the brightness. The problem is definitely nvidia drivers for me, but it looks very same - the brightness applet says "Cannot get laptop panel brightness". Another thing that stopped working is the Gnome display resolution manager (I had two separate displays set up there before installing drivers, it worked perfectly, but stopped doing that after), but this is a bit offtopic.

By the way, the command from the second post here returned YES, the second command however did nothing to the brightness - it just returned 5.

I tried following the advice in this thread and added following to /etc/init.d/gdm:

echo -n 100 > /proc/acpi/video/NVID/LCD/brightness

That worked (sort of), now I get full brightness at startup, but it still cannot be changed on running system. Even sudo'ing that command at runtime returns Permission denied, so I'm not sure how that could be used to help anything.