1 ==================== 1 ====================
2 One-shot LED Trigger 2 One-shot LED Trigger
3 ==================== 3 ====================
4 4
5 This is a LED trigger useful for signaling the 5 This is a LED trigger useful for signaling the user of an event where there are
6 no clear trap points to put standard led-on an 6 no clear trap points to put standard led-on and led-off settings. Using this
7 trigger, the application needs only to signal 7 trigger, the application needs only to signal the trigger when an event has
8 happened, then the trigger turns the LED on an 8 happened, then the trigger turns the LED on and then keeps it off for a
9 specified amount of time. 9 specified amount of time.
10 10
11 This trigger is meant to be usable both for sp 11 This trigger is meant to be usable both for sporadic and dense events. In the
12 first case, the trigger produces a clear singl 12 first case, the trigger produces a clear single controlled blink for each
13 event, while in the latter it keeps blinking a 13 event, while in the latter it keeps blinking at constant rate, as to signal
14 that the events are arriving continuously. 14 that the events are arriving continuously.
15 15
16 A one-shot LED only stays in a constant state 16 A one-shot LED only stays in a constant state when there are no events. An
17 additional "invert" property specifies if the 17 additional "invert" property specifies if the LED has to stay off (normal) or
18 on (inverted) when not rearmed. 18 on (inverted) when not rearmed.
19 19
20 The trigger can be activated from user space o 20 The trigger can be activated from user space on led class devices as shown
21 below:: 21 below::
22 22
23 echo oneshot > trigger 23 echo oneshot > trigger
24 24
25 This adds sysfs attributes to the LED that are 25 This adds sysfs attributes to the LED that are documented in:
26 Documentation/ABI/testing/sysfs-class-led-trig 26 Documentation/ABI/testing/sysfs-class-led-trigger-oneshot
27 27
28 Example use-case: network devices, initializat 28 Example use-case: network devices, initialization::
29 29
30 echo oneshot > trigger # set trigger for thi 30 echo oneshot > trigger # set trigger for this led
31 echo 33 > delay_on # blink at 1 / (33 + 31 echo 33 > delay_on # blink at 1 / (33 + 33) Hz on continuous traffic
32 echo 33 > delay_off 32 echo 33 > delay_off
33 33
34 interface goes up:: 34 interface goes up::
35 35
36 echo 1 > invert # set led as normally-on, tu 36 echo 1 > invert # set led as normally-on, turn the led on
37 37
38 packet received/transmitted:: 38 packet received/transmitted::
39 39
40 echo 1 > shot # led starts blinking, ignored 40 echo 1 > shot # led starts blinking, ignored if already blinking
41 41
42 interface goes down:: 42 interface goes down::
43 43
44 echo 0 > invert # set led as normally-off, t 44 echo 0 > invert # set led as normally-off, turn the led off
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