[mythtv-users] Power Saving Frontend Ideas

[Paul Bender]

Jose Bernardo Bandos Rodrigues wrote:
> On Sun, Apr 13, 2008 at 9:21 PM, Paul Bender <pebender at san.rr.com> wrote:
>>  S3 (suspend to RAM) controlled using remote control.
> 
> How did you do it? I can't get my MCE remote to wakeup my frontend
> (FIC Spectra based, a Advent DHE-500).

S3 is problematic. In may cases, the motherboard BIOS and/or video card 
BIOS is broken, requiring special treatment to get S3 to work correctly 
or preventing S3 from working correctly.

Assuming that you have S3 working and assuming you motherboard supports 
USB wake from S3, then being able to wake from the remote requires 
enabling the USB host controller (to which you have the remote receiver 
connected) to wake the motherboard from S3.

First, you need to enable it on the motherboard. This is usually done 
with a motherboard jumper but is sometimes done with a BIOS setting. 
Essentially, this is allowing the host controller and the connected USB 
devices to be powered while the motherboard is in S3. If possible, only 
enable wake from S3 on the host controller to which the remote receiver 
is connected and do not connect any other USB devices to the host 
controller. Some USB devices (e.g. some iMON LCD/VFD displays) do not 
play well with wake from S3 (e.g. they wake the motherboard immediately).

Second, you need to enable it in the kernel. This can be done through 
the proc file system. To determine whether or not it is already enabled use

cat /proc/acpi/wakeup

The USB host controllers will be called something like USB?. If you do 
not know which device is the appropriate USB host controller, then you 
can find it by finding the appropriate PCI sysfs node from the output of

udevinfo \
   --attribute-walk \
   --path=`udevinfo --query=path --name=/dev/lirc0'

assuming that your remote receiver is the device /dev/lirc0. Once you 
know the device, then you can enable wakeup for the device (assuming it 
is disabled) using

echo {device} > /proc/acpi/wakeup