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| author | Saravana Kannan <saravanak@google.com> | 2019-09-05 00:11:21 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-04 18:29:50 +0300 |
| commit | e2ae9bcc4aaacda04edb75c4eea93384719efaa5 (patch) | |
| tree | 9c01d02d0a1e67c4de38c94e27180f9411fc850d /Documentation | |
| parent | 372a67c0c5ef63f55bd1eb480d9555328d8ec0f2 (diff) | |
| download | linux-e2ae9bcc4aaacda04edb75c4eea93384719efaa5.tar.xz | |
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 <saravanak@google.com>
Link: https://lore.kernel.org/r/20190904211126.47518-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/driver-api/device_link.rst | 3 |
1 files changed, 2 insertions, 1 deletions
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()`.) |