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authorKim Phillips <kim.phillips@freescale.com>2014-06-02 19:42:58 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-08 15:31:26 -0700
commit3d713e0e382e6fcfb4bba1501645b66c129ad60b (patch)
tree9b47c38f09df44537b163ca18eabc8c979aa1f04 /Documentation/ABI
parent1cec24c59b4a133fc9c83912996168f511075485 (diff)
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driver core: platform: add device binding path 'driver_override'
Needed by platform device drivers, such as the upcoming vfio-platform driver, in order to bypass the existing OF, ACPI, id_table and name string matches, and successfully be able to be bound to any device, like so: echo vfio-platform > /sys/bus/platform/devices/fff51000.ethernet/driver_override echo fff51000.ethernet > /sys/bus/platform/devices/fff51000.ethernet/driver/unbind echo fff51000.ethernet > /sys/bus/platform/drivers_probe This mimics "PCI: Introduce new device binding path using pci_dev.driver_override", which is an interface enhancement for more deterministic PCI device binding, e.g., when in the presence of hotplug. Reviewed-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Alexander Graf <agraf@suse.de> Reviewed-by: Stuart Yoder <stuart.yoder@freescale.com> Signed-off-by: Kim Phillips <kim.phillips@freescale.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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+What: /sys/bus/platform/devices/.../driver_override
+Date: April 2014
+Contact: Kim Phillips <kim.phillips@freescale.com>
+Description:
+ This file allows the driver for a device to be specified which
+ will override standard OF, ACPI, ID table, and name matching.
+ When specified, only a driver with a name matching the value
+ written to driver_override will have an opportunity to bind
+ to the device. The override is specified by writing a string
+ to the driver_override file (echo vfio-platform > \
+ driver_override) and may be cleared with an empty string
+ (echo > driver_override). This returns the device to standard
+ matching rules binding. Writing to driver_override does not
+ automatically unbind the device from its current driver or make
+ any attempt to automatically load the specified driver. If no
+ driver with a matching name is currently loaded in the kernel,
+ the device will not bind to any driver. This also allows
+ devices to opt-out of driver binding using a driver_override
+ name such as "none". Only a single driver may be specified in
+ the override, there is no support for parsing delimiters.
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