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46 lines
1.4 KiB
46 lines
1.4 KiB
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USB port LED trigger |
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This LED trigger can be used for signalling to the user a presence of USB device |
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in a given port. It simply turns on LED when device appears and turns it off |
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when it disappears. |
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It requires selecting USB ports that should be observed. All available ones are |
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listed as separated entries in a "ports" subdirectory. Selecting is handled by |
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echoing "1" to a chosen port. |
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Please note that this trigger allows selecting multiple USB ports for a single |
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LED. |
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This can be useful in two cases: |
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1) Device with single USB LED and few physical ports |
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In such a case LED will be turned on as long as there is at least one connected |
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USB device. |
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2) Device with a physical port handled by few controllers |
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Some devices may have one controller per PHY standard. E.g. USB 3.0 physical |
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port may be handled by ohci-platform, ehci-platform and xhci-hcd. If there is |
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only one LED user will most likely want to assign ports from all 3 hubs. |
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This trigger can be activated from user space on led class devices as shown |
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below:: |
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echo usbport > trigger |
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This adds sysfs attributes to the LED that are documented in: |
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Documentation/ABI/testing/sysfs-class-led-trigger-usbport |
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Example use-case:: |
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echo usbport > trigger |
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echo 1 > ports/usb1-port1 |
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echo 1 > ports/usb2-port1 |
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cat ports/usb1-port1 |
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echo 0 > ports/usb1-port1
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