Problem with LCD backlight remaining on during ACPI sleep

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Revision as of 13:35, 29 November 2005 by 213.39.155.53 (Talk) (hwclock has nothing to do with this solution)
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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.