[PATCH v2 5/7] USB: of: fix root-hub device-tree node handling

Johan Hovold
2017-06-06T16:03:24Z

In an attempt to work around a pinmux over-allocation issue in driver
core, commit dc5878abf49c ("usb: core: move root hub's device node
assignment after it is added to bus") moved the device-tree node
assignment until after the root hub had been registered.

This not only makes the device-tree node unavailable to the usb driver
during probe, but also prevents the of_node from being linked to in
sysfs and causes a race with user-space for the (recently added) devspec
attribute.

Use the new device_set_of_node_from_dev() helper to reuse the node of
the sysdev device, something which now prevents driver core from trying
to reclaim any pinctrl pins during probe.

Fixes: dc5878abf49c ("usb: core: move root hub's device node assignment after it is added to bus")
Fixes: 51fa91475e43 ("usb/core: Added devspec sysfs entry for devices behind the usb hub")
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/usb/core/hcd.c | 2 --
drivers/usb/core/usb.c | 4 ++--
2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 5dea98358c05..2cff59e9c268 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1076,7 +1076,6 @@ static void usb_deregister_bus (struct usb_bus *bus)
static int register_root_hub(struct usb_hcd *hcd)
{
struct device *parent_dev = hcd->self.controller;
- struct device *sysdev = hcd->self.sysdev;
struct usb_device *usb_dev = hcd->self.root_hub;
const int devnum = 1;
int retval;
@@ -1123,7 +1122,6 @@ static int register_root_hub(struct usb_hcd *hcd)
/* Did the HC die before the root hub was registered? */
if (HCD_DEAD(hcd))
usb_hc_died (hcd); /* This time clean up */
- usb_dev->dev.of_node = sysdev->of_node;
}
mutex_unlock(&usb_bus_idr_lock);

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 62e1906bb2f3..17681d5638ac 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -416,8 +416,7 @@ static void usb_release_dev(struct device *dev)

usb_destroy_configuration(udev);
usb_release_bos_descriptor(udev);
- if (udev->parent)
- of_node_put(dev->of_node);
+ of_node_put(dev->of_node);
usb_put_hcd(hcd);
kfree(udev->product);
kfree(udev->manufacturer);
@@ -616,6 +615,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
dev->route = 0;

dev->dev.parent = bus->controller;
+ device_set_of_node_from_dev(&dev->dev, bus->sysdev);
dev_set_name(&dev->dev, "usb%d", bus->busnum);
root_hub = 1;
} else {
--
2.13.0