Re: ACPI S3 suspend and LCD backlight

[Matthew Garrett <mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org>]

On Sat, Nov 12, 2005 at 10:39:04PM -0700, yauh-acpi-CDzBh2wLF5MAvxtiuMwx3w@public.gmane.org wrote:

> 	It appears something in the ACPI suspend code turns on the
> LCD backlight to print out the diagnostic messages. Is there any 
> way to prevent this? Alternatively, is there a place in the drive
> I can add a sequence to turn off the display just before it goes
> to sleep?

No, the ACPI suspend code doesn't do this (as far as I can tell). If you 
suspend from X, the kernel will switch away from X and X will restore 
the console state - which probably includes switching the backlight back 
on.

> The xset turns off the backlight but as soon as it gets to the echo 3 line,
> the LCD comes on and displays the ACPI status messages. It then then 
> proceeds to blank the screen but does NOT turn off the backlight.
> If there is no way to disable the messages, I was hoping there is a
> place I can hook into to twiddle the bit needed to disable the backlight.
> Loading the video support module gives me an empty /proc/acpi/video directory.

Try grabbing vbetool and do something like

FGCONSOLE=`fgconsole`
chvt 12
vbetool dpms off
echo -n 3 >/proc/acpi/sleep
chvt $FGCONSOLE

-- 
Matthew Garrett | mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org


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