Commit Graph

2 Commits

Author SHA1 Message Date
Heikki Krogerus
5c54fcac9a usb: roles: Take care of driver module reference counting
This fixes potential "BUG: unable to handle kernel paging
request at ..." from happening.

Fixes: fde0aa6c17 ("usb: common: Small class for USB role switches")
Cc: <stable@vger.kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-09-20 13:20:24 +02:00
Heikki Krogerus
fde0aa6c17 usb: common: Small class for USB role switches
USB role switch is a device that can be used to choose the
data role for USB connector. With dual-role capable USB
controllers, the controller itself will be the switch, but
on some platforms the USB host and device controllers are
separate IPs and there is a mux between them and the
connector. On those platforms the mux driver will need to
register the switch.

With USB Type-C connectors, the host-to-device relationship
is negotiated over the Configuration Channel (CC). That
means the USB Type-C drivers need to be in control of the
role switch. The class provides a simple API for the USB
Type-C drivers for the control.

For other types of USB connectors (mainly microAB) the class
provides user space control via sysfs attribute file that
can be used to request role swapping from the switch.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-22 13:40:10 +01:00