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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,
        Dennis Wassenberg <dennis.wassenberg@secunet.com>,
        Mathias Nyman <mathias.nyman@linux.intel.com>
Subject: [PATCH 4.4 01/86] usb: core: Fix hub port connection events lost
Date:   Thu, 29 Nov 2018 15:11:26 +0100
Message-Id: <20181129140109.929428667@linuxfoundation.org>
In-Reply-To: <20181129140109.832117862@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dennis Wassenberg <dennis.wassenberg@secunet.com>

commit 22454b79e6de05fa61a2a72d00d2eed798abbb75 upstream.

This will clear the USB_PORT_FEAT_C_CONNECTION bit in case of a hub port reset
only if a device is was attached to the hub port before resetting the hub port.

Using a Lenovo T480s attached to the ultra dock it was not possible to detect
some usb-c devices at the dock usb-c ports because the hub_port_reset code
will clear the USB_PORT_FEAT_C_CONNECTION bit after the actual hub port reset.
Using this device combo the USB_PORT_FEAT_C_CONNECTION bit was set between the
actual hub port reset and the clear of the USB_PORT_FEAT_C_CONNECTION bit.
This ends up with clearing the USB_PORT_FEAT_C_CONNECTION bit after the
new device was attached such that it was not detected.

This patch will not clear the USB_PORT_FEAT_C_CONNECTION bit if there is
currently no device attached to the port before the hub port reset.
This will avoid clearing the connection bit for new attached devices.

Signed-off-by: Dennis Wassenberg <dennis.wassenberg@secunet.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/core/hub.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2757,7 +2757,9 @@ static int hub_port_reset(struct usb_hub
 					USB_PORT_FEAT_C_BH_PORT_RESET);
 			usb_clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_PORT_LINK_STATE);
-			usb_clear_port_feature(hub->hdev, port1,
+
+			if (udev)
+				usb_clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_CONNECTION);
 
 			/*