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driver core: fw_devlink: Add support for FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD

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If a parent device is also a supplier to a child device, fw_devlink=on by
design delays the probe() of the child device until the probe() of the
parent finishes successfully.

However, some drivers of such parent devices (where parent is also a
supplier) expect the child device to finish probing successfully as soon as
they are added using device_add() and before the probe() of the parent
device has completed successfully. One example of such a case is discussed
in the link mentioned below.

Add a flag to make fw_devlink=on not enforce these supplier-consumer
relationships, so these drivers can continue working.

Link: https://lore.kernel.org/netdev/CAGETcx_uj0V4DChME-gy5HGKTYnxLBX=TH2rag29f_p=UcG+Tg@mail.gmail.com/
Fixes: ea718c6990 ("Revert "Revert "driver core: Set fw_devlink=on by default""")
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210915170940.617415-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Saravana Kannan 2021-09-15 10:09:38 -07:00 committed by Greg Kroah-Hartman
parent 2de9d8e0d2
commit 5501765a02
2 changed files with 27 additions and 3 deletions
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19
drivers/base/core.c
View file

@ -1722,6 +1722,25 @@ static int fw_devlink_create_devlink(struct device *con,
struct device *sup_dev;
int ret = 0;
/*
* In some cases, a device P might also be a supplier to its child node
* C. However, this would defer the probe of C until the probe of P
* completes successfully. This is perfectly fine in the device driver
* model. device_add() doesn't guarantee probe completion of the device
* by the time it returns.
*
* However, there are a few drivers that assume C will finish probing
* as soon as it's added and before P finishes probing. So, we provide
* a flag to let fw_devlink know not to delay the probe of C until the
* probe of P completes successfully.
*
* When such a flag is set, we can't create device links where P is the
* supplier of C as that would delay the probe of C.
*/
if (sup_handle->flags & FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD &&
fwnode_is_ancestor_of(sup_handle, con->fwnode))
return -EINVAL;
sup_dev = get_dev_from_fwnode(sup_handle);
if (sup_dev) {
/*

11
include/linux/fwnode.h
View file

@ -22,10 +22,15 @@ struct device;
* LINKS_ADDED: The fwnode has already be parsed to add fwnode links.
* NOT_DEVICE: The fwnode will never be populated as a struct device.
* INITIALIZED: The hardware corresponding to fwnode has been initialized.
* NEEDS_CHILD_BOUND_ON_ADD: For this fwnode/device to probe successfully, its
* driver needs its child devices to be bound with
* their respective drivers as soon as they are
* added.
*/
#define FWNODE_FLAG_LINKS_ADDED BIT(0)
#define FWNODE_FLAG_NOT_DEVICE BIT(1)
#define FWNODE_FLAG_INITIALIZED BIT(2)
#define FWNODE_FLAG_LINKS_ADDED BIT(0)
#define FWNODE_FLAG_NOT_DEVICE BIT(1)
#define FWNODE_FLAG_INITIALIZED BIT(2)
#define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD BIT(3)
struct fwnode_handle {
struct fwnode_handle *secondary;