linux kernel usb suspended

by · 2020年08月01日 · 791 Words · ~2min reading time | Improve on

Suspend USB devices (turn the power off)

EC20 USB 1-1

注意。这个答案中的信息与旧的内核相关（最多2.6.32）。有关新内核的信息，请参阅tlwhitec。

disable external wake-up; do this only once

echo disabled > /sys/bus/usb/devices/usb1/power/wakeup

echo on > /sys/bus/usb/devices/usb1/power/level # turn on
echo suspend > /sys/bus/usb/devices/usb1/power/level # turn off 已经弃用了
WARNING! power/level is deprecated; use power/control instead

（你可能需要将usb1更改为usb n）

Additionally, from Documentation/usb/power-management.txt:

power/control

        This file contains one of two words: "on" or "auto".
        You can write those words to the file to change the
        device's setting.

        "on" means that the device should be resumed and
        autosuspend is not allowed.  (Of course, system
        suspends are still allowed.)

        "auto" is the normal state in which the kernel is
        allowed to autosuspend and autoresume the device.

        (In kernels up to 2.6.32, you could also specify
        "suspend", meaning that the device should remain
        suspended and autoresume was not allowed.  This
        setting is no longer supported.)

To enforce suspend immediately when device is unused:

echo -n "0" >$DEV_POWER_PATH"/power/autosuspend_delay_ms"
echo -n "auto" >$DEV_POWER_PATH"/power/control"

Make the device was not used

rmmod drv_name # see result of lsmod

Power on:

echo -n "2000" >$DEV_POWER_PATH"/power/autosuspend_delay_ms"
echo -n "on" >$DEV_POWER_PATH"/power/control"

Make the device was used.

modprobe drv_name

echo "on" > "/sys/bus/usb/devices/2-1.7/power/control"
echo "2000" > "/sys/bus/usb/devices/2-1.7/power/autosuspend_delay_ms"
echo -n "2-1.7" > /sys/bus/usb/drivers/usb/bind

遍历usb

for i in /sys/bus/usb/devices/usb* ; do echo "suspend" > $i/power/level; done

uhubctl

You could use my tool uhubctl - command line utility to control USB power per port for compatible USB hubs.

It works only on hubs that support per-port power switching, but note that many modern motherboards have USB hubs that support this feature.

To compile:

git clone https://github.com/mvp/uhubctl
cd uhubctl
make
To install system-wide as /usr/sbin/uhubctl:

sudo make install
To list status of all hubs, their locations and ports that can be controlled by uhubctl:

sudo uhubctl
(you can avoid using sudo if you configure udev USB permissions).

To turn off power on port 5 of single compatible hub:

sudo uhubctl -a 0 -p 5
If you have more than one compatible hub connected, use -l to specify hub location to control it:

sudo uhubctl -a 0 -p 5 -l 3-1.2
To toggle power off then on:

sudo uhubctl -a 2 -p 5
Note that USB 3.0 hubs are also supported, and quite a few new USB 3.0 hubs actually work well.