[wellylug] usb behavior
filmtransfer.ec at gmail.com
Wed Apr 2 14:59:40 NZDT 2014
nope not UEFI, thanks. Unless I have it wrong I am not too familiar with
this Uefi stuff.
However I think I am on something here... that's an old "todo" but seems
to be consistent with my observation
USB power management
A feature not yet implemented is USB power management. This is currently
work in progress. With this feature, active USB devices are
automatically deactivated when not used. A good example where this makes
sense might be a web cam. However, this cannot be set on all systems and
all devices automatically. A whitelist is needed, which makes the
implementation a no-one-liner.
For activating it, userspace can write to the sysfs files in
/sys/bus/usb/devices/*/power/level for each individual USB device like
for dev in /sys/bus/usb/devices/*/power/level; do
echo auto > $dev
This can save up to about 2 W, depending on the hardware in use. You can
enable laptop-mode-tools to control this by editing
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