linux suspend/resume with hal/dbus

**wirelessdreamer** · 08-30-2007, 09:03 AM

I'm starting this thread to get some feedback from people that ideally have first hand experience with linux boxes in their car.

i've been going back and forth between if i want to get a mini-itx system for my car, or use and old laptop. Cost, and features though are making me look at the old laptop as the best route to go, here's how i see it so far

Mini itx
2ghz c7 board+ ram+cf storage ~$250

power supply/startup controller $100 +

nice case $70

$420

Laptop

pIII dell latitude - ~$100 on ebay, already have one though

power supply ~$75 for a ac inverter for the original power brick then run a normal computer power supply for the 12v regulated my lilliput display needs

$175

using the laptop also has the advantage that my carpc now has its own battery (ignoring the display) so i won't need to worry that much about killing my battery in my car if i decide to use it when the car's off.

I think its also possible to read acpi information with hal so when the laptop gets unplugged (+12 accesory tied into a transtor on the ac inverter's power switch) it suspends, and then when it gets plugged in, it resumes. i'm pretty sure i know how to initiate the suspend, but i'm not that sure about the resume, seeing how the laptop is suspended.

i also know i can get processor temp readings correctly from the dell, monitor the fans, watch the battery level, and give it 2 batteries, so it deffinately seems the best way to go.

how many people out there use laptops for their car pc's and how do you usually handle suspend/resum?

**tripzero** · 08-30-2007, 01:05 PM

if the laptop suspends, it should automatically resume when it starts up again. Unless you are using suspend2 (which requires a separate kernel patch) your resume should be automatic.

I personally use suspend2 and have modified acpid to hibernate when a poweroff even has occured.

Good luck

**dupa2** · 08-30-2007, 11:24 PM

why suspend/resume at all?
if your laptop is around 800-1000MHz, it's powerfull enough to do cold start/shutdown.
I'm using via c3 1GHz car pc, and can optimize the kernel and startup scripts to start in about 15sec.
My main problem is BIOS that takes 10-12sec to boot, which I plan to replace with linuxbios (lots of soldering though since my bios chip is soldered on mainboard).
With linuxbios it would start within 10-12sec, which is pretty much same as resume from S3 state.

**wirelessdreamer** · 08-31-2007, 03:05 PM

i had my desktop down to about 20 seconds before, right now the laptop i'm goin to use is at 40 seconds though, i should be able to get it to 30 pretty easy, but i don't think it can hit the 10-15 sec mark on a cold boot.

dupa are you goin to be at the chicago meet this month on the 30th? i should be able to make it again and have my setup with me.

**shotgunefx** · 08-31-2007, 03:24 PM

I'm using a laptop (2.6.20 suspend2). For shutdown, I have a script that is run on a power down event which sets creates a file under /var and writes the time to it. Also have a power on even that removes it.

I have a cronjob that runs every 3 minutes and checks for the file, and if found reads it, if the time is greater than X minutes, it deletes the file and issues a hibernate command.

The only problem I have is every once in awhile, hibernate fails, I fixed this by adding a --force to the command.

To start my monitor, I have a lilliput with auto power on, this is powered by a PIC that waits X seconds after receiving power to flip the relay. This relay also powers my line converter and poweron lead to my amp, so I avoid thumping.

**shotgunefx** · 08-31-2007, 03:57 PM

A little more detail...

I modified /etc/acpi/power.sh to call the following script right after the includes.

/etc/acpi/battery.pl

Code:

#!/usr/bin/perl

warn "On Battery [$ARGV[0]\n";

my $status = `/usr/bin/acpi -Ba`;

#AC Adapter 1: on-line

my $stat_file = '/var/run/battery_status';

if ($status =~m/on-line/i){
  warn "On AC\n";
  unlink ($stat_file) if (-e $stat_file);
}else{
  warn "On Battery\n";
  open (FH, ">$stat_file") or die "Couldn't open battery status file [$stat_file] : $!";
  print FH time(),"\n";

}

Here is the cronjob... /usr/local/bin/checkpower

Code:

#!/usr/bin/perl

use warnings;

$ENV{PATH} = '/sbin:/usr/sbin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games';

my $SHUTDOWN_SECS = 60 * 5; # How long to wait before shutdown
my $file = '/var/run/battery_status';

my $batt_time;
if (-e $file){
   open (FH, "<$file") or die "Couldn't read file: $!";
   $batt_time = <FH>;
   chomp($batt_time);
   print "On battery for ",time()-$batt_time," seconds\n";
   if (time() - $batt_time > $SHUTDOWN_SECS){
     warn "Shutting down...";
     unlink($file); # Clean up
     warn "Hibernating\n";
     system('/usr/local/sbin/hibernate --force');
   }else{
       print $SHUTDOWN_SECS - (time() - $batt_time), " seconds until shutdown\n";

   }

}else{
  # "Nothing to do";
}

**wirelessdreamer** · 09-03-2007, 11:52 AM

thanks for posting the script, just the type of thing i was planning on, i'm still a few weeks off from testing this setup in my car, this'll let me spend time on more important things now

**shotgunefx** · 09-03-2007, 02:45 PM

Originally Posted by wirelessdreamer

thanks for posting the script, just the type of thing i was planning on, i'm still a few weeks off from testing this setup in my car, this'll let me spend time on more important things now

No problem, have some other odds and ends like that. A script for daylight, nighttime detection, etc. Maybe I'll do a little write up. Should document it better even for my own needs. So many tweaks here and there, if I have to to it over again, I'd never remember everything off the top of my head.