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usb: core: added uevent for over-current

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After commit 1cbd53c8cd ("usb: core: introduce per-port over-current
counters") usb ports expose a sysfs value 'over_current_count'
to user space. This value on its own is not very useful as it requires
manual polling.

As a solution, fire a udev event from the usb hub device that specifies
the values 'OVER_CURRENT_PORT' and 'OVER_CURRENT_COUNT' that indicate
the path of the usb port where the over-current event occurred and the
value of 'over_current_count' in sysfs. Additionally, call
sysfs_notify() so the sysfs value supports poll().

Signed-off-by: Jon Flatley <jflat@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jon Flatley
2018-09-20 10:17:54 -07:00
committed by Greg Kroah-Hartman
parent ea3b4d5523
commit 201af55da8
2 changed files with 44 additions and 1 deletions
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9
Documentation/ABI/testing/sysfs-bus-usb
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@@ -219,7 +219,14 @@ Description:
ports and report them to the kernel. This attribute is to expose
the number of over-current situation occurred on a specific port
to user space. This file will contain an unsigned 32 bit value
which wraps to 0 after its maximum is reached.
which wraps to 0 after its maximum is reached. This file supports
poll() for monitoring changes to this value in user space.
Any time this value changes the corresponding hub device will send a
udev event with the following attributes:
OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX
OVER_CURRENT_COUNT=[current value of this sysfs attribute]
What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
Date: November 2015