[PATCH 4.4 01/86] usb: core: Fix hub port connection events lost

From: Greg Kroah-Hartman
Date: Thu Nov 29 2018 - 09:17:22 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Dennis Wassenberg <dennis.wassenberg@xxxxxxxxxxx>

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@xxxxxxxxxxx>
Acked-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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_clear_port_feature(hub->hdev, port1,
- usb_clear_port_feature(hub->hdev, port1,
+ if (udev)
+ usb_clear_port_feature(hub->hdev, port1,