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UPSTREAM: driver core: fw_devlink: Detect supplier devices that will never be added

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During the initial parsing of firmware by fw_devlink, fw_devlink might
infer that some supplier firmware nodes would get populated as devices.
But the inference is not always correct. This patch tries to logically
detect and fix such mistakes as boot progresses or more devices probe.

fw_devlink makes a fundamental assumption that once a device binds to a
driver, it will populate (i.e: add as struct devices) all the child
firmware nodes that could be populated as devices (if they aren't
populated already).

So, whenever a device probes, we check all its child firmware nodes. If
a child firmware node has a corresponding device populated, we don't
modify the child node or its descendants. However, if a child firmware
node has not been populated as a device, we delete all the fwnode links
where the child node or its descendants are suppliers. This ensures that
no other device is blocked on a firmware node that will never be
populated as a device. We also mark such fwnodes as NOT_DEVICE, so that
no new fwnode links are created with these nodes as suppliers.

Fixes: e590474768f1 ("driver core: Set fw_devlink=on by default")
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210205222644.2357303-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 9528e0d9c10027ae80e2aab36e30a1f730b1bbf9)
Bug: 181264536
Change-Id: I76f38f22cb11b85a8b6104c131924357d5254640
This commit is contained in:
Saravana Kannan
2021-02-05 14:26:37 -08:00
parent f1ed75c87e
commit fe5ff1ae21
2 changed files with 30 additions and 3 deletions
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2
include/linux/fwnode.h
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@@ -19,8 +19,10 @@ struct device;
* fwnode link flags
*
* LINKS_ADDED: The fwnode has already be parsed to add fwnode links.
* NOT_DEVICE: The fwnode will never be populated as a struct device.
*/
#define FWNODE_FLAG_LINKS_ADDED BIT(0)
#define FWNODE_FLAG_NOT_DEVICE BIT(1)
struct fwnode_handle {
struct fwnode_handle *secondary;