From: Saravana Kannan <saravanak@google.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ard Biesheuvel <ardb@kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Saravana Kannan <saravanak@google.com>,
Tomi Valkeinen <tomi.valkeinen@ti.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Grygorii Strashko <grygorii.strashko@ti.com>,
kernel-team@android.com, linux-acpi@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
devicetree@vger.kernel.org
Subject: [PATCH v1 17/18] driver core: Add helper functions to convert fwnode links to device links
Date: Wed, 4 Nov 2020 15:23:54 -0800 [thread overview]
Message-ID: <20201104232356.4038506-18-saravanak@google.com> (raw)
In-Reply-To: <20201104232356.4038506-1-saravanak@google.com>
Add helper functions __fw_devlink_link_to_consumers() and
__fw_devlink_link_to_suppliers() that convert fwnode links to device
links.
__fw_devlink_link_to_consumers() is for creating:
- Device links between a newly added device and all its consumer devices
that have been added to driver core.
- Proxy SYNC_STATE_ONLY device links between the newly added device and
the parent devices of all its consumers that have not been added to
driver core yet.
__fw_devlink_link_to_suppliers() is for creating:
- Device links between a newly added device and all its supplier devices
- Proxy SYNC_STATE_ONLY device links between the newly added device and
all the supplier devices of its child device nodes.
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
drivers/base/core.c | 228 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 228 insertions(+)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index d51dd564add1..0c87ff949d81 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1585,6 +1585,234 @@ static struct device *fwnode_get_next_parent_dev(struct fwnode_handle *fwnode)
return dev;
}
+/**
+ * fw_devlink_create_devlink - Create a device link from a consumer to fwnode
+ * @con - Consumer device for the device link
+ * @sup - fwnode handle of supplier
+ *
+ * This function will try to create a device link between the consumer and the
+ * supplier devices.
+ *
+ * The supplier has to be provided as a fwnode because incorrect cycles in
+ * fwnode links can sometimes cause the supplier device to never be created.
+ * This function detects such cases and returns an error if a device link being
+ * created in invalid.
+ *
+ * Returns,
+ * 0 on successfully creating a device link
+ * -EINVAL if the device link being attempted is invalid
+ * -EAGAIN if the device link needs to be attempted again in the future
+ */
+static int fw_devlink_create_devlink(struct device *con,
+ struct fwnode_handle *sup, u32 flags)
+{
+ struct device *sup_dev, *sup_par_dev;
+ int ret = 0;
+
+ sup_dev = get_dev_from_fwnode(sup);
+ /*
+ * If we can't find the supplier device from its fwnode, it might be
+ * due to a cyclic dependcy between fwnodes. Some of these cycles can
+ * be broken by applying logic. Check for these types of cycles and
+ * break them so that devices in the cycle probe properly.
+ */
+ if (!sup_dev) {
+ /*
+ * DL_FLAG_SYNC_STATE_ONLY doesn't block probing and supports
+ * cycles. So cycle detection isn't necessary and shouldn't be
+ * done.
+ */
+ if (flags & DL_FLAG_SYNC_STATE_ONLY)
+ return -EAGAIN;
+
+ sup_par_dev = fwnode_get_next_parent_dev(sup);
+
+ /*
+ * If the supplier's parent is dependent on the consumer, then
+ * the consumer-supplier dependency is a false dependency. So,
+ * treat it as an invalid link.
+ */
+ if (sup_par_dev && device_is_dependent(con, sup_par_dev)) {
+ dev_dbg(con, "Not linking to %pfwP - False link\n",
+ sup);
+ ret = -EINVAL;
+ } else {
+ /*
+ * Can't check for cycles or no cycles. So let's try
+ * again later.
+ */
+ ret = -EAGAIN;
+ }
+
+ put_device(sup_par_dev);
+ return ret;
+ }
+
+ /*
+ * If we get this far and fail, this is due to cycles in device links.
+ * Just give up on this link and treat it as invalid.
+ */
+ if (!device_link_add(con, sup_dev, flags))
+ ret = -EINVAL;
+ put_device(sup_dev);
+
+ return ret;
+}
+
+/**
+ * __fw_devlink_link_to_consumers - Create device links to consumers of a device
+ * @dev - Device that needs to be linked to its consumers
+ *
+ * This function looks at all the consumer fwnodes of @dev and creates device
+ * links between the consumer device and @dev (supplier).
+ *
+ * If the consumer device has not been added yet, then this function creates a
+ * SYNC_STATE_ONLY link between @dev (supplier) and the closest ancestor device
+ * of the consumer fwnode. This is necessary to make sure @dev doesn't get a
+ * sync_state() callback before the real consumer device gets to be added and
+ * then probed.
+ *
+ * Once device links are created from the real consumer to @dev (supplier), the
+ * fwnode links are deleted.
+ */
+static void __fw_devlink_link_to_consumers(struct device *dev)
+{
+ struct fwnode_handle *fwnode = dev->fwnode;
+ struct fwnode_link *link, *tmp;
+
+ list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook) {
+ u32 dl_flags = fw_devlink_get_flags();
+ struct device *con_dev;
+ bool own_link = true;
+ int ret;
+
+ con_dev = get_dev_from_fwnode(link->consumer);
+ /*
+ * If consumer device is not available yet, make a "proxy"
+ * SYNC_STATE_ONLY link from the consumer's parent device to
+ * the supplier device. This is necessary to make sure the
+ * supplier doesn't get a sync_state() callback before the real
+ * consumer can create a device link to the supplier.
+ *
+ * This proxy link step is needed to handle the case where the
+ * consumer's parent device is added before the supplier.
+ */
+ if (!con_dev) {
+ con_dev = fwnode_get_next_parent_dev(link->consumer);
+ /*
+ * However, if the consumer's parent device is also the
+ * parent of the supplier, don't create a
+ * consumer-supplier link from the parent to its child
+ * device. Such a dependency is impossible.
+ */
+ if (con_dev &&
+ fwnode_is_ancestor_of(con_dev->fwnode, fwnode)) {
+ put_device(con_dev);
+ con_dev = NULL;
+ } else {
+ own_link = false;
+ dl_flags = DL_FLAG_SYNC_STATE_ONLY;
+ }
+ }
+
+ if (!con_dev)
+ continue;
+
+ ret = fw_devlink_create_devlink(con_dev, fwnode, dl_flags);
+ put_device(con_dev);
+ if (!own_link || ret == -EAGAIN)
+ continue;
+
+ list_del(&link->s_hook);
+ list_del(&link->c_hook);
+ kfree(link);
+ }
+}
+
+/**
+ * __fw_devlink_link_to_suppliers - Create device links to suppliers of a device
+ * @dev - The consumer device that needs to be linked to its suppliers
+ * @fwnode - Root of the fwnode tree that is used to create device links
+ *
+ * This function looks at all the supplier fwnodes of fwnode tree rooted at
+ * @fwnode and creates device links between @dev (consumer) and all the
+ * supplier devices of the entire fwnode tree at @fwnode. See
+ * fw_devlink_create_devlink() for more details.
+ *
+ * The function creates normal (non-SYNC_STATE_ONLY) device links between @dev
+ * and the real suppliers of @dev. Once these device links are created, the
+ * fwnode links are deleted. When such device links are successfully created,
+ * this function is called recursively on those supplier devices. This is
+ * needed to detect and break some invalid cycles in fwnode links.
+ *
+ * In addition, it also looks at all the suppliers of the entire fwnode tree
+ * because some of the child devices of @dev that have not been added yet
+ * (because @dev hasn't probed) might already have their suppliers added to
+ * driver core. So, this function creates SYNC_STATE_ONLY device links between
+ * @dev (consumer) and these suppliers to make sure they don't execute their
+ * sync_state() callbacks before these child devices have a chance to create
+ * their device links. The fwnode links that correspond to the child devices
+ * aren't delete because they are needed later to create the device links
+ * between the real consumer and supplier devices.
+ */
+static void __fw_devlink_link_to_suppliers(struct device *dev,
+ struct fwnode_handle *fwnode)
+{
+ bool own_link = (dev->fwnode == fwnode);
+ struct fwnode_link *link, *tmp;
+ struct fwnode_handle *child = NULL;
+ u32 dl_flags;
+
+ if (own_link)
+ dl_flags = fw_devlink_get_flags();
+ else
+ dl_flags = DL_FLAG_SYNC_STATE_ONLY;
+
+ list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook) {
+ int ret;
+ struct device *sup_dev;
+ struct fwnode_handle *sup = link->supplier;
+
+ ret = fw_devlink_create_devlink(dev, sup, dl_flags);
+ if (!own_link || ret == -EAGAIN)
+ continue;
+
+ list_del(&link->s_hook);
+ list_del(&link->c_hook);
+ kfree(link);
+
+ /* If no device link was created, nothing more to do. */
+ if (ret)
+ continue;
+
+ /*
+ * If a device link was successfully created to a supplier, we
+ * now need to try and link the supplier to all its suppliers.
+ *
+ * This is needed to detect and delete false dependencies in
+ * fwnode links that haven't been converted to a device link
+ * yet. See comments in fw_devlink_create_devlink() for more
+ * details on the false dependency.
+ *
+ * Without deleting these false dependencies, some devices will
+ * never probe because they'll keep waiting for their false
+ * dependency fwnode links to be converted to device links.
+ */
+ sup_dev = get_dev_from_fwnode(sup);
+ __fw_devlink_link_to_suppliers(sup_dev, sup_dev->fwnode);
+ put_device(sup_dev);
+ }
+
+ /*
+ * Make "proxy" SYNC_STATE_ONLY device links to represent the needs of
+ * all the descendants. This proxy link step is needed to handle the
+ * case where the supplier is added before the consumer's parent device
+ * (@dev).
+ */
+ while ((child = fwnode_get_next_available_child_node(fwnode, child)))
+ __fw_devlink_link_to_suppliers(dev, child);
+}
+
static void fw_devlink_link_device(struct device *dev)
{
int fw_ret;
--
2.29.1.341.ge80a0c044ae-goog
next prev parent reply other threads:[~2020-11-04 23:24 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-04 23:23 [PATCH v1 00/18] Refactor fw_devlink to significantly improve boot time Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 01/18] Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()" Saravana Kannan
2020-11-05 9:34 ` Greg Kroah-Hartman
2020-11-05 23:19 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 02/18] Revert "driver core: Rename dev_links_info.defer_sync to defer_hook" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 03/18] Revert "driver core: Don't do deferred probe in parallel with kernel_init thread" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 04/18] Revert "driver core: Remove check in driver_deferred_probe_force_trigger()" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 05/18] Revert "of: platform: Batch fwnode parsing when adding all top level devices" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 06/18] Revert "driver core: fw_devlink: Add support for batching fwnode parsing" Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 07/18] driver core: Add fwnode_init() Saravana Kannan
2020-11-05 9:36 ` Greg Kroah-Hartman
2020-11-05 23:20 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 08/18] driver core: Add fwnode link support Saravana Kannan
2020-11-16 15:51 ` Rafael J. Wysocki
2020-11-21 1:59 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 09/18] driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links Saravana Kannan
2020-11-16 15:57 ` Rafael J. Wysocki
2020-11-21 1:59 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 10/18] device property: Add fwnode_is_ancestor_of() Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 11/18] driver core: Redefine the meaning of fwnode_operations.add_links() Saravana Kannan
2020-11-16 16:16 ` Rafael J. Wysocki
2020-11-21 1:59 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 12/18] driver core: Add fw_devlink_parse_fwtree() Saravana Kannan
2020-11-16 16:25 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 13/18] driver core: Add fwnode_get_next_parent_dev() helper function Saravana Kannan
2020-11-16 16:27 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 14/18] driver core: Use device's fwnode to check if it is waiting for suppliers Saravana Kannan
2020-11-16 16:34 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 15/18] of: property: Update implementation of add_links() to create fwnode links Saravana Kannan
2020-11-05 9:42 ` Greg Kroah-Hartman
2020-11-05 23:25 ` Saravana Kannan
2020-11-06 1:24 ` Saravana Kannan
2020-11-06 7:22 ` Greg Kroah-Hartman
2020-11-06 7:41 ` Saravana Kannan
2020-11-06 7:51 ` Greg Kroah-Hartman
2020-11-06 8:29 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 16/18] efi: " Saravana Kannan
2020-11-05 9:43 ` Greg Kroah-Hartman
2020-11-05 23:27 ` Saravana Kannan
2020-11-06 6:45 ` Greg Kroah-Hartman
2020-11-04 23:23 ` Saravana Kannan [this message]
2020-11-05 9:43 ` [PATCH v1 17/18] driver core: Add helper functions to convert fwnode links to device links Greg Kroah-Hartman
2020-11-05 23:32 ` Saravana Kannan
2020-11-06 7:24 ` Greg Kroah-Hartman
2020-11-06 7:43 ` Saravana Kannan
2020-11-16 16:57 ` Rafael J. Wysocki
2020-11-21 2:00 ` Saravana Kannan
2020-11-04 23:23 ` [PATCH v1 18/18] driver core: Refactor fw_devlink feature Saravana Kannan
2020-11-04 23:26 ` [PATCH v1 00/18] Refactor fw_devlink to significantly improve boot time Saravana Kannan
2020-11-06 5:09 ` Laurent Pinchart
2020-11-06 8:36 ` Saravana Kannan
2020-11-06 12:46 ` Grygorii Strashko
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