Difference between revisions of "Problem with LCD backlight remaining on during ACPI sleep"

From ThinkWiki
Jump to: navigation, search
(Affected Models: added mine.)
(hwclock has nothing to do with this solution)
Line 15: Line 15:
 
will work, but only in a text-mode virtual terminal.  If X is running, the light apparently comes back on when the kernel switches to text mode prior to sleeping.  The solution in that case it to switch to a text mode console first.
 
will work, but only in a text-mode virtual terminal.  If X is running, the light apparently comes back on when the kernel switches to text mode prior to sleeping.  The solution in that case it to switch to a text mode console first.
  
I use the following script to suspend my machine.  The hwclock lines compensate for the clock running at double speed during suspend (this is fixed in the 2.6.11 release candidate kernels, various distributions may backport the fix).
 
 
  logger "Software suspend to ram."
 
  logger "Software suspend to ram."
sync
 
 
  FGCONSOLE=`fgconsole`
 
  FGCONSOLE=`fgconsole`
/sbin/hwclock --systohc
 
 
  chvt 1
 
  chvt 1
 
  radeontool light off
 
  radeontool light off
 
  echo -n 3 >/proc/acpi/sleep
 
  echo -n 3 >/proc/acpi/sleep
/sbin/hwclock --adjust
 
/sbin/hwclock --hctosys
 
 
  logger "Woke up from suspend."
 
  logger "Woke up from suspend."
 
  radeontool light on
 
  radeontool light on

Revision as of 14:35, 29 November 2005

Problem description

On some models the LCD backlight remains on during ACPI sleep.

Affected Models

(according to the relevant bug on the Kernel bug tracker (bug 2576))

Partial solution

If the ThinkPad has a radeon video chip, then switching off the light with the command

 radeontool light off

will work, but only in a text-mode virtual terminal. If X is running, the light apparently comes back on when the kernel switches to text mode prior to sleeping. The solution in that case it to switch to a text mode console first.

logger "Software suspend to ram."
FGCONSOLE=`fgconsole`
chvt 1
radeontool light off
echo -n 3 >/proc/acpi/sleep
logger "Woke up from suspend."
radeontool light on
chvt $FGCONSOLE

Improvements are clearly possible. :-)

A similar script can be found on the acpid configuration HOWTO page.