[PATCH 1/5] xhci: keep port link_inactive and connected flags in sync when polled

[Mathias Nyman <mathias.nyman@linux.intel.com>]

Update port 'link_inactive' and 'connected' flags even if xHC isn't
generating port change events.

xHC only generates port change events on port changes after old port
change bits are cleared. Hub driver is often kept up to date
by polling the port status.

Sashiko reported a possible case where all port changes after a port
reset take place before hub driver clears the reset change bit.
This way the port can end up connected and fully running with link
in u0 without a port event clearing the 'link_inactive' or setting
the 'connected' flags.

A protocol STALL in this state would set EP_DROP_PENDING, and
prevent all future URBs for the endpoint.

Fix this by also updating the flags during get_port_status(), when
hub driver is polling the port state.

Fixes: 6895dbdc19d9 ("xhci: give back TDs and clean up ep0 after disconnect")
Link: https://lore.kernel.org/linux-usb/sashiko-outbox-190046@kernel.org/
Cc: stable <stable@kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-hub.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 470bafe1802b..55430b673f1e 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1166,6 +1166,12 @@ static u32 xhci_get_port_status(struct usb_hcd *hcd, struct xhci_bus_state *bus_
 	if (portsc & PORT_RESET)
 		status |= USB_PORT_STAT_RESET;
 
+	/* track connect and link error status when hub is polling */
+	if (!(portsc & PORT_RESET)) {
+		port->link_inactive = (portsc & PORT_PLS_MASK) == XDEV_INACTIVE;
+		port->connected = !!(portsc & PORT_CONNECT);
+	}
+
 	/* USB2 and USB3 specific bits, including Port Link State */
 	if (hcd->speed >= HCD_USB3)
 		xhci_get_usb3_port_status(port, &status, portsc);
-- 
2.43.0