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Commit 822e87b7 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Greg Kroah-Hartman
Browse files

driver core: Add device link flag DL_FLAG_AUTOPROBE_CONSUMER 



commit e7dd40105aac9ba051e44ad711123bc53a5e4c71 upstream.

Add a new device link flag, DL_FLAG_AUTOPROBE_CONSUMER, to request the
driver core to probe for a consumer driver automatically after binding
a driver to the supplier device on a persistent managed device link.

As unbinding the supplier driver on a managed device link causes the
consumer driver to be detached from its device automatically, this
flag provides a complementary mechanism which is needed to address
some "composite device" use cases.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1f5102cb

Documentation/driver-api/device_link.rst

+9 −0
Original line number Diff line number Diff line
@@ -94,6 +94,15 @@ Similarly, when the device link is added from supplier's ``->probe`` callback, 
``DL_FLAG_AUTOREMOVE_SUPPLIER`` causes the device link to be automatically

purged when the supplier fails to probe or later unbinds.



If neither ``DL_FLAG_AUTOREMOVE_CONSUMER`` nor ``DL_FLAG_AUTOREMOVE_SUPPLIER``

is set, ``DL_FLAG_AUTOPROBE_CONSUMER`` can be used to request the driver core

to probe for a driver for the consumer driver on the link automatically after

a driver has been bound to the supplier device.



Note, however, that any combinations of ``DL_FLAG_AUTOREMOVE_CONSUMER``,

``DL_FLAG_AUTOREMOVE_SUPPLIER`` or ``DL_FLAG_AUTOPROBE_CONSUMER`` with

``DL_FLAG_STATELESS`` are invalid and cannot be used.



Limitations

===========

drivers/base/core.c

+15 −1
Original line number Diff line number Diff line
@@ -195,6 +195,12 @@ void device_pm_move_to_tail(struct device *dev) 
 * the link will be maintained until one of the devices pointed to by it (either

 * the consumer or the supplier) is unregistered.

 *

 * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and

 * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent

 * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can

 * be used to request the driver core to automaticall probe for a consmer

 * driver after successfully binding a driver to the supplier device.

 *

 * The combination of DL_FLAG_STATELESS and either DL_FLAG_AUTOREMOVE_CONSUMER

 * or DL_FLAG_AUTOREMOVE_SUPPLIER set in @flags at the same time is invalid and

 * will cause NULL to be returned upfront.
@@ -215,7 +221,12 @@ struct device_link *device_link_add(struct device *consumer, 


	if (!consumer || !supplier ||

	    (flags & DL_FLAG_STATELESS &&

	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER | DL_FLAG_AUTOREMOVE_SUPPLIER)))

	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |

		      DL_FLAG_AUTOREMOVE_SUPPLIER |

		      DL_FLAG_AUTOPROBE_CONSUMER)) ||

	    (flags & DL_FLAG_AUTOPROBE_CONSUMER &&

	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |

		      DL_FLAG_AUTOREMOVE_SUPPLIER)))

		return NULL;



	if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
@@ -576,6 +587,9 @@ void device_links_driver_bound(struct device *dev) 


		WARN_ON(link->status != DL_STATE_DORMANT);

		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);



		if (link->flags & DL_FLAG_AUTOPROBE_CONSUMER)

			driver_deferred_probe_add(link->consumer);

	}



	list_for_each_entry(link, &dev->links.suppliers, c_node) {

drivers/base/dd.c

+1 −1
Original line number Diff line number Diff line
@@ -116,7 +116,7 @@ static void deferred_probe_work_func(struct work_struct *work) 
}

static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);



static void driver_deferred_probe_add(struct device *dev)

void driver_deferred_probe_add(struct device *dev)

{

	mutex_lock(&deferred_probe_mutex);

	if (list_empty(&dev->p->deferred_probe)) {

include/linux/device.h

+3 −0
Original line number Diff line number Diff line
@@ -339,6 +339,7 @@ struct device *driver_find_device(struct device_driver *drv, 
				  struct device *start, void *data,

				  int (*match)(struct device *dev, void *data));



void driver_deferred_probe_add(struct device *dev);

int driver_deferred_probe_check_state(struct device *dev);



/**
@@ -824,12 +825,14 @@ enum device_link_state { 
 * PM_RUNTIME: If set, the runtime PM framework will use this link.

 * RPM_ACTIVE: Run pm_runtime_get_sync() on the supplier during link creation.

 * AUTOREMOVE_SUPPLIER: Remove the link automatically on supplier driver unbind.

 * AUTOPROBE_CONSUMER: Probe consumer driver automatically after supplier binds.

 */

#define DL_FLAG_STATELESS		BIT(0)

#define DL_FLAG_AUTOREMOVE_CONSUMER	BIT(1)

#define DL_FLAG_PM_RUNTIME		BIT(2)

#define DL_FLAG_RPM_ACTIVE		BIT(3)

#define DL_FLAG_AUTOREMOVE_SUPPLIER	BIT(4)

#define DL_FLAG_AUTOPROBE_CONSUMER	BIT(5)



/**

 * struct device_link - Device link representation.