1 ====================
2 USB port LED trigger
3 ====================
4
5 This LED trigger can be used for signalling to
6 in a given port. It simply turns on LED when d
7 when it disappears.
8
9 It requires selecting USB ports that should be
10 listed as separated entries in a "ports" subdi
11 echoing "1" to a chosen port.
12
13 Please note that this trigger allows selecting
14 LED.
15
16 This can be useful in two cases:
17
18 1) Device with single USB LED and few physical
19 ==============================================
20
21 In such a case LED will be turned on as long a
22 USB device.
23
24 2) Device with a physical port handled by few
25 ==============================================
26
27 Some devices may have one controller per PHY s
28 port may be handled by ohci-platform, ehci-pla
29 only one LED user will most likely want to ass
30
31
32 This trigger can be activated from user space
33 below::
34
35 echo usbport > trigger
36
37 This adds sysfs attributes to the LED that are
38 Documentation/ABI/testing/sysfs-class-led-trig
39
40 Example use-case::
41
42 echo usbport > trigger
43 echo 1 > ports/usb1-port1
44 echo 1 > ports/usb2-port1
45 cat ports/usb1-port1
46 echo 0 > ports/usb1-port1
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