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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Mathias Nyman <mathias.nyman@linux.intel.com>,
        Chris Chiu <chris.chiu@canonical.com>,
        Kishon Vijay Abraham I <kishon@ti.com>
Subject: [PATCH 5.18 034/879] xhci: Set HCD flag to defer primary roothub registration
Date:   Tue,  7 Jun 2022 18:52:32 +0200
Message-Id: <20220607165003.665844631@linuxfoundation.org>
In-Reply-To: <20220607165002.659942637@linuxfoundation.org>
References: <20220607165002.659942637@linuxfoundation.org>
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From: Kishon Vijay Abraham I <kishon@ti.com>

commit b7a4f9b5d0e4b6dd937678c546c0b322dd1a4054 upstream.

Set "HCD_FLAG_DEFER_RH_REGISTER" to hcd->flags in xhci_run() to defer
registering primary roothub in usb_add_hcd() if xhci has two roothubs.
This will make sure both primary roothub and secondary roothub will be
registered along with the second HCD.
This is required for cold plugged USB devices to be detected in certain
PCIe USB cards (like Inateck USB card connected to AM64 EVM or J7200 EVM).

This patch has been added and reverted earier as it triggered a race
in usb device enumeration.
That race is now fixed in 5.16-rc3, and in stable back to 5.4
commit 6cca13de26ee ("usb: hub: Fix locking issues with address0_mutex")
commit 6ae6dc22d2d1 ("usb: hub: Fix usb enumeration issue due to address0
race")

[minor rebase change, and commit message update -Mathias]

CC: stable@vger.kernel.org # 5.4+
Suggested-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Tested-by: Chris Chiu <chris.chiu@canonical.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Link: https://lore.kernel.org/r/20220510091630.16564-3-kishon@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/host/xhci.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -696,6 +696,8 @@ int xhci_run(struct usb_hcd *hcd)
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"Finished xhci_run for USB2 roothub");
 
+	set_bit(HCD_FLAG_DEFER_RH_REGISTER, &hcd->flags);
+
 	xhci_create_dbc_dev(xhci);
 
 	xhci_debugfs_init(xhci);