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driver core: Add device links from fwnode only for the primary device

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Sometimes, more than one (generally two) device can point to the same
fwnode.  However, only one device is set as the fwnode's device
(fwnode->dev) and can be looked up from the fwnode.

Typically, only one of these devices actually have a driver and actually
probe. If we create device links for all these devices, then the
suppliers' of these devices (with the same fwnode) will never get a
sync_state() call because one of their consumer devices will never probe
(because they don't have a driver).

So, create device links only for the device that is considered as the
fwnode's device.

One such example of this is the PCI bridge platform_device and the
corresponding pci_bus device. Both these devices will have the same
fwnode. It's the platform_device that is registered first and is set as
the fwnode's device. Also the platform_device is the one that actually
probes. Without this patch none of the suppliers of a PCI bridge
platform_device would get a sync_state() callback.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200321045448.15192-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Saravana Kannan 2020-03-20 21:54:48 -07:00 committed by Greg Kroah-Hartman
parent b94b807e8c
commit 4dbe191c04
1 changed files with 6 additions and 2 deletions
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8
drivers/base/core.c
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@ -2404,6 +2404,7 @@ int device_add(struct device *dev)
struct class_interface *class_intf;
int error = -EINVAL, fw_ret;
struct kobject *glue_dir = NULL;
bool is_fwnode_dev = false;
dev = get_device(dev);
if (!dev)
@ -2501,8 +2502,10 @@ int device_add(struct device *dev)
kobject_uevent(&dev->kobj, KOBJ_ADD);
if (dev->fwnode && !dev->fwnode->dev)
if (dev->fwnode && !dev->fwnode->dev) {
dev->fwnode->dev = dev;
is_fwnode_dev = true;
}
/*
* Check if any of the other devices (consumers) have been waiting for
@ -2518,7 +2521,8 @@ int device_add(struct device *dev)
*/
device_link_add_missing_supplier_links();
if (fw_devlink_flags && fwnode_has_op(dev->fwnode, add_links)) {
if (fw_devlink_flags && is_fwnode_dev &&
fwnode_has_op(dev->fwnode, add_links)) {
fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
if (fw_ret == -ENODEV)
device_link_wait_for_mandatory_supplier(dev);