Problem with LCD backlight remaining on during ACPI sleep
Contents
Problem description
On some models the LCD backlight remains on during ACPI sleep.
Affected Models
- ThinkPad 390X with kernel boot option ACPI=force
- ThinkPad A30
- ThinkPad A31p
- ThinkPad T30
- ThinkPad X31,X32
- ThinkPad R51
(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. :-)
On the X32, at least, the bios will switch off the screen by default on a lid close, and suspending to ram interrupts this, and the screen will turn back on. This can be fixed by simply adding "sleep 5" before "echo -n 3 > /proc/acpi/sleep". The suspend will take longer, but the screen will remain off.
A similar script can be found on the acpid configuration HOWTO page.
Using Powersaved
If you use powersaved you can just edit the two scripts prepare_suspend_to_ram and restore_after_suspend_to_ram which are stored in /usr/lib/powersave/scripts/
add two lines to prepare_suspend_to_ram nearly at the end of the script:
# insert the next two lines: chvt 1 radeontool light off # this changes to a console nr. 1 and switches the light off progress_finish $SCRIPT_RETURN $EV_ID 0 "prepare_sleep finished successfully for $1" EXIT 0
and to restore_after_suspend_to_ram
# insert the next two lines: radeontool light on chvt 7 # this switching the light on and changes to display #7 (where the x-server runs) - #you can change it to another display if you want... #(the way doing this with a variable like in the script above doesn't work, because it can't be stored between #the two different scripts. # $SCRIPT_RETURN is called in restore_after_sleep. EXIT 0
Than you can suspend to ram with /usr/bin/powersave -u or just configure powersaved in a way that it suspends to ram when your notebook is closed. (As a frontend kpowersave is recomended).
Using s2ram
Just using the s2ram command from the uswsusp (Userspace Suspend) package should do the trick by appending the "-r" option (-r, --radeontool: turn off the backlight on radeons before suspending.).
A simple change in a start-up file in OpenSuse 11.3 corrected this problem
1. Open a terminal and type gnomesu gedit /etc/grub/menu.lst. When prompted, type root password and click OK.
2. Gedit opens with the menu.lst file displayed. Down the page a bit, there are several sections that begin with "###Don't change this comment"
3. The first section gives details for the default boot operating system. Somewhere in this long spec, find "vga=0x314" or vga=(something specific to your system).
4. Just before or after this vga spec, type "nomodeset" separated from the vga spec by a space.
5. Save the file and reboot. In OpenSuse, suspend/resume now works normally.
