kernel_optimize_test/Documentation/ABI/testing/sysfs-bus-platform
Kim Phillips 3d713e0e38 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>
2014-07-08 15:31:26 -07:00

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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.