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@xxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
---
drivers/base/core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index fc6a60998cd6..5e3cc1651c78 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -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);
--
2.25.1.696.g5e7596f4ac-goog
