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| author | Michael Grzeschik <m.grzeschik@pengutronix.de> | 2022-06-07 13:45:22 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-12 06:49:46 +0200 |
| commit | f061f43d7418cb62b8d073e221ec75d3f5b89e17 (patch) | |
| tree | 59d311ae1af0105d165ee26ec129c122c9e6e545 /Documentation/ABI/testing/sysfs-bus-usb | |
| parent | 5fd6c4f0a649c956b2c50c18e0da765b7f5e3eff (diff) | |
| download | lwn-f061f43d7418cb62b8d073e221ec75d3f5b89e17.tar.gz lwn-f061f43d7418cb62b8d073e221ec75d3f5b89e17.zip | |
usb: hub: port: add sysfs entry to switch port power
In some cases the port of an hub needs to be disabled or switched off
and on again. E.g. when the connected device needs to be re-enumerated.
Or it needs to be explicitly disabled while the rest of the usb tree
stays working.
For this purpose this patch adds an sysfs switch to enable/disable the
port on any hub. In the case the hub is supporting power switching, the
power line will be disabled to the connected device.
When the port gets disabled, the associated device gets disconnected and
removed from the logical usb tree. No further device will be enumerated
on that port until the port gets enabled again.
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220607114522.3359148-1-m.grzeschik@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-usb')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 7efe31ed3a25..568103d3376e 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -253,6 +253,17 @@ Description: only if the system firmware is capable of describing the connection between a port and its connector. +What: /sys/bus/usb/devices/.../<hub_interface>/port<X>/disable +Date: June 2022 +Contact: Michael Grzeschik <m.grzeschik@pengutronix.de> +Description: + This file controls the state of a USB port, including + Vbus power output (but only on hubs that support + power switching -- most hubs don't support it). If + a port is disabled, the port is unusable: Devices + attached to the port will not be detected, initialized, + or enumerated. + What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout Date: May 2013 Contact: Mathias Nyman <mathias.nyman@linux.intel.com> |