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

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Date:   Tue, 30 May 2017 18:25:52 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Peter Chen <peter.chen@...escale.com>,
        Rob Herring <robh@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        Sricharan R <sricharan@...eaurora.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        linux-pm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>
Subject: [PATCH 5/7] USB: of: fix root-hub device-tree node handling

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@...nel.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