From bcbbcfd57247f4c2976055995e5760fb576aae1e Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Mon, 28 Oct 2019 15:00:23 -0700 Subject: [PATCH] driver core: Allow a device to wait on optional suppliers Before this change, if a device is waiting on suppliers, it's assumed that all those suppliers are needed for the device to probe successfully. This change allows marking a devices as waiting only on optional suppliers. This allows a device to wait on suppliers (and link to them as soon as they are available) without preventing the device from being probed. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20191028220027.251605-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 28 +++++++++++++++++++++++++--- include/linux/device.h | 3 +++ 2 files changed, 28 insertions(+), 3 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 17ed054..48cd43a 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -480,13 +480,25 @@ EXPORT_SYMBOL_GPL(device_link_add); * This function is NOT meant to be called from the probe function of the * consumer but rather from code that creates/adds the consumer device. */ -static void device_link_wait_for_supplier(struct device *consumer) +static void device_link_wait_for_supplier(struct device *consumer, + bool need_for_probe) { mutex_lock(&wfs_lock); list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers); + consumer->links.need_for_probe = need_for_probe; mutex_unlock(&wfs_lock); } +static void device_link_wait_for_mandatory_supplier(struct device *consumer) +{ + device_link_wait_for_supplier(consumer, true); +} + +static void device_link_wait_for_optional_supplier(struct device *consumer) +{ + device_link_wait_for_supplier(consumer, false); +} + /** * device_link_add_missing_supplier_links - Add links from consumer devices to * supplier devices, leaving any @@ -656,7 +668,8 @@ int device_links_check_suppliers(struct device *dev) * probe. */ mutex_lock(&wfs_lock); - if (!list_empty(&dev->links.needs_suppliers)) { + if (!list_empty(&dev->links.needs_suppliers) && + dev->links.need_for_probe) { mutex_unlock(&wfs_lock); return -EPROBE_DEFER; } @@ -760,6 +773,15 @@ void device_links_driver_bound(struct device *dev) { struct device_link *link; + /* + * If a device probes successfully, it's expected to have created all + * the device links it needs to or make new device links as it needs + * them. So, it no longer needs to wait on any suppliers. + */ + mutex_lock(&wfs_lock); + list_del_init(&dev->links.needs_suppliers); + mutex_unlock(&wfs_lock); + device_links_write_lock(); list_for_each_entry(link, &dev->links.consumers, s_node) { @@ -2393,7 +2415,7 @@ int device_add(struct device *dev) if (fwnode_has_op(dev->fwnode, add_links) && fwnode_call_int_op(dev->fwnode, add_links, dev)) - device_link_wait_for_supplier(dev); + device_link_wait_for_mandatory_supplier(dev, true); bus_probe_device(dev); if (parent) diff --git a/include/linux/device.h b/include/linux/device.h index 82890e1..d1bcc8f 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -1155,6 +1155,8 @@ enum dl_dev_state { * @consumers: List of links to consumer devices. * @needs_suppliers: Hook to global list of devices waiting for suppliers. * @defer_sync: Hook to global list of devices that have deferred sync_state. + * @need_for_probe: If needs_suppliers is on a list, this indicates if the + * suppliers are needed for probe or not. * @status: Driver status information. */ struct dev_links_info { @@ -1162,6 +1164,7 @@ struct dev_links_info { struct list_head consumers; struct list_head needs_suppliers; struct list_head defer_sync; + bool need_for_probe; enum dl_dev_state status; }; -- 2.7.4