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Message-Id: <20200317065452.236670-5-saravanak@google.com>
Date: Mon, 16 Mar 2020 23:54:50 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: stable@...r.kernel.org, Jonathan Corbet <corbet@....net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Matthias Brugger <matthias.bgg@...il.com>
Cc: Saravana Kannan <saravanak@...gle.com>, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, kernel-team@...roid.com,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH v1 4/6] driver core: Add device link flag DL_FLAG_AUTOPROBE_CONSUMER
From: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
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: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
(cherry picked from commit e7dd40105aac9ba051e44ad711123bc53a5e4c71)
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
Documentation/driver-api/device_link.rst | 9 +++++++++
drivers/base/core.c | 16 +++++++++++++++-
drivers/base/dd.c | 2 +-
include/linux/device.h | 3 +++
4 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/Documentation/driver-api/device_link.rst b/Documentation/driver-api/device_link.rst
index e249e074a8d2..c764755121c7 100644
--- a/Documentation/driver-api/device_link.rst
+++ b/Documentation/driver-api/device_link.rst
@@ -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
===========
diff --git a/drivers/base/core.c b/drivers/base/core.c
index d8273792950b..3495da13b18a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -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) {
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 5f6416e6ba96..caaeb7910a04 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -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)) {
diff --git a/include/linux/device.h b/include/linux/device.h
index c74ce473589a..7569cff2f4dc 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -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.
--
2.25.1.481.gfbce0eb801-goog
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