I recently began using my laptop at my desk with a USB keyboard and mouse, and I thought I would explain how to set up Ubuntu so that USB peripherals will wake up your computer from sleep mode. This is convenient if you have your laptop set up such that the lid is closed and inaccessible.
In Ubuntu, the way to set this up is to edit the file located at /proc/acpi/wakeup. To see the current contents of this file do this:
% cat /proc/acpi/wakeup
Device S-state Status Sysfs node
P0P2 S4 disabled
P0P1 S4 disabled pci:0000:00:1e.0
MC97 S4 disabled
HDAC S4 disabled pci:0000:00:1b.0
P0P4 S4 disabled pci:0000:00:1c.0
P0P5 S4 disabled pci:0000:00:1c.1
P0P7 S4 disabled
P0P8 S4 disabled
P0P9 S4 disabled
USB0 S3 disabled pci:0000:00:1d.0
USB1 S3 disabled pci:0000:00:1d.1
USB2 S3 disabled pci:0000:00:1d.2
USB3 S3 disabled pci:0000:00:1d.3
EUSB S3 disabled pci:0000:00:1d.7
P0P6 S4 disabled pci:0000:00:1c.2
SLPB S4 *enabled
This shows you a number of devices, most of which I don't claim to understand. The ones to notice are the USB ones, which you will see are disabled by default.
Once these are toggled on, your computer will wake up from sleep when USB peripherals are used. To toggle one of these on, as root, run:
echo "USB0" > /proc/acpi/wakeup
This will toggle USB0 from disabled to enabled. To check this, run cat /proc/acpi/wakeup again. You should see that it's enabled, and you should be able to test this by suspending your computer.
This will set up your computer to wake up from USB...for now. To make it work after your computer has been restarted, you will need to write a short init script named wake.sh with the following contents:
#!/bin/bash
echo "USB0" > /proc/acpi/wakeup
Save this file to /etc/init.d, and make it executable by running:
chmod +x wake.sh
Finally, once this file is in /etc/init.d, and is executable, as root run:
update-rc.d wake.sh defaults
That will make init know about the file, and run it at startup. Happy awakenings!
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