From e2ae9bcc4aaacda04edb75c4eea93384719efaa5 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Wed, 4 Sep 2019 14:11:21 -0700 Subject: driver core: Add support for linking devices during device addition The firmware corresponding to a device (dev.fwnode) might be able to provide functional dependency information between a device and its supplier and consumer devices. Tracking this functional dependency allows optimizing device probe order and informing a supplier when all its consumers have probed (and thereby actively managing their resources). The existing device links feature allows tracking and using supplier-consumer relationships. So, this patch adds the add_links() fwnode callback to allow firmware to create device links for each device as the device is added. However, when consumer devices are added, they might not have a supplier device to link to despite needing mandatory resources/functionality from one or more suppliers. A waiting_for_suppliers list is created to track such consumers and retry linking them when new devices get added. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20190904211126.47518-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- Documentation/driver-api/device_link.rst | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'Documentation/driver-api') diff --git a/Documentation/driver-api/device_link.rst b/Documentation/driver-api/device_link.rst index 1b5020ec6517..bc2d89af88ce 100644 --- a/Documentation/driver-api/device_link.rst +++ b/Documentation/driver-api/device_link.rst @@ -281,7 +281,8 @@ State machine :c:func:`driver_bound()`.) * Before a consumer device is probed, presence of supplier drivers is - verified by checking that links to suppliers are in ``DL_STATE_AVAILABLE`` + verified by checking the consumer device is not in the wait_for_suppliers + list and by checking that links to suppliers are in ``DL_STATE_AVAILABLE`` state. The state of the links is updated to ``DL_STATE_CONSUMER_PROBE``. (Call to :c:func:`device_links_check_suppliers()` from :c:func:`really_probe()`.) -- cgit