[PATCH 2/4][SRU][F/H] usb: core: hcd: Add support for deferring roothub registration

[Chris Chiu]

From: Kishon Vijay Abraham I <kishon at ti.com>

BugLink: https://bugs.launchpad.net/bugs/1945211

It has been observed with certain PCIe USB cards (like Inateck connected
to AM64 EVM or J7200 EVM) that as soon as the primary roothub is
registered, port status change is handled even before xHC is running
leading to cold plug USB devices not detected. For such cases, registering
both the root hubs along with the second HCD is required. Add support for
deferring roothub registration in usb_add_hcd(), so that both primary and
secondary roothubs are registered along with the second HCD.

CC: stable at vger.kernel.org # 5.4+
Suggested-by: Mathias Nyman <mathias.nyman at linux.intel.com>
Tested-by: Chris Chiu <chris.chiu at canonical.com>
Acked-by: Alan Stern <stern at rowland.harvard.edu>
Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
Link: https://lore.kernel.org/r/20210909064200.16216-2-kishon@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 58877b0824da15698bd85a0a9dbfa8c354e6ecb7)
Signed-off-by: Chris Chiu <chris.chiu at canonical.com>
---
 drivers/usb/core/hcd.c  | 29 +++++++++++++++++++++++------
 include/linux/usb/hcd.h |  2 ++
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index ad5a0f405a75..aadb13b0667f 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2645,6 +2645,7 @@ int usb_add_hcd(struct usb_hcd *hcd,
 {
 	int retval;
 	struct usb_device *rhdev;
+	struct usb_hcd *shared_hcd;
 
 	if (!hcd->skip_phy_initialization && usb_hcd_is_primary_hcd(hcd)) {
 		hcd->phy_roothub = usb_phy_roothub_alloc(hcd->self.sysdev);
@@ -2801,13 +2802,26 @@ int usb_add_hcd(struct usb_hcd *hcd,
 		goto err_hcd_driver_start;
 	}
 
+	/* starting here, usbcore will pay attention to the shared HCD roothub */
+	shared_hcd = hcd->shared_hcd;
+	if (!usb_hcd_is_primary_hcd(hcd) && shared_hcd && HCD_DEFER_RH_REGISTER(shared_hcd)) {
+		retval = register_root_hub(shared_hcd);
+		if (retval != 0)
+			goto err_register_root_hub;
+
+		if (shared_hcd->uses_new_polling && HCD_POLL_RH(shared_hcd))
+			usb_hcd_poll_rh_status(shared_hcd);
+	}
+
 	/* starting here, usbcore will pay attention to this root hub */
-	retval = register_root_hub(hcd);
-	if (retval != 0)
-		goto err_register_root_hub;
+	if (!HCD_DEFER_RH_REGISTER(hcd)) {
+		retval = register_root_hub(hcd);
+		if (retval != 0)
+			goto err_register_root_hub;
 
-	if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
-		usb_hcd_poll_rh_status(hcd);
+		if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
+			usb_hcd_poll_rh_status(hcd);
+	}
 
 	return retval;
 
@@ -2851,6 +2865,7 @@ EXPORT_SYMBOL_GPL(usb_add_hcd);
 void usb_remove_hcd(struct usb_hcd *hcd)
 {
 	struct usb_device *rhdev = hcd->self.root_hub;
+	bool rh_registered;
 
 	dev_info(hcd->self.controller, "remove, state %x\n", hcd->state);
 
@@ -2861,6 +2876,7 @@ void usb_remove_hcd(struct usb_hcd *hcd)
 
 	dev_dbg(hcd->self.controller, "roothub graceful disconnect\n");
 	spin_lock_irq (&hcd_root_hub_lock);
+	rh_registered = hcd->rh_registered;
 	hcd->rh_registered = 0;
 	spin_unlock_irq (&hcd_root_hub_lock);
 
@@ -2870,7 +2886,8 @@ void usb_remove_hcd(struct usb_hcd *hcd)
 	cancel_work_sync(&hcd->died_work);
 
 	mutex_lock(&usb_bus_idr_lock);
-	usb_disconnect(&rhdev);		/* Sets rhdev to NULL */
+	if (rh_registered)
+		usb_disconnect(&rhdev);		/* Sets rhdev to NULL */
 	mutex_unlock(&usb_bus_idr_lock);
 
 	/*
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 96281cd50ff6..67cfe8c25bd8 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -124,6 +124,7 @@ struct usb_hcd {
 #define HCD_FLAG_RH_RUNNING		5	/* root hub is running? */
 #define HCD_FLAG_DEAD			6	/* controller has died? */
 #define HCD_FLAG_INTF_AUTHORIZED	7	/* authorize interfaces? */
+#define HCD_FLAG_DEFER_RH_REGISTER	8	/* Defer roothub registration */
 
 	/* The flags can be tested using these macros; they are likely to
 	 * be slightly faster than test_bit().
@@ -134,6 +135,7 @@ struct usb_hcd {
 #define HCD_WAKEUP_PENDING(hcd)	((hcd)->flags & (1U << HCD_FLAG_WAKEUP_PENDING))
 #define HCD_RH_RUNNING(hcd)	((hcd)->flags & (1U << HCD_FLAG_RH_RUNNING))
 #define HCD_DEAD(hcd)		((hcd)->flags & (1U << HCD_FLAG_DEAD))
+#define HCD_DEFER_RH_REGISTER(hcd) ((hcd)->flags & (1U << HCD_FLAG_DEFER_RH_REGISTER))
 
 	/*
 	 * Specifies if interfaces are authorized by default
-- 
2.25.1