[Bug 19410] Re: Laptop backlight does not turn off

[Id2ndR]

I encountred the same trouble with HP nc6400 laptop.
I was able to switch the backlight off with this command: sudo vbetool dpms standby

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https://bugs.launchpad.net/bugs/19410

Title:
  Laptop backlight does not turn off

Status in “acpi-support” package in Ubuntu:
  Fix Released

Bug description:
  On my laptop, the backlight never turns off unless the lid is closed (appears to
  be a hardware switch, cutting the power to the display).

  xset -q reports Acpi working and returns the monitor state correctly (also when
  supposedly off).
  xset dpms force off blanks the screen, but the backlight stays on.  The same
  goes for vbetool.

  DPMS is enabled in xorg.conf and reported loaded succesfully in
  xorg.log.

  As far as I can tell, the issue is somewhere in the kernel ACPI drivers.  There
  are a number of people reporting this on several different machines with both
  ATI and Nvidia cards (maybe others).
  most files in /proc/acpi/video/VGA/LCD report <not supported>.

  My laptop is a HP Pavilion zv5474EA with an Nvidia card (Nvidia drivers).  It is
  running an up-to-date Hoary.

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