The first U3 wake signal by the host may be lost if the USB 3 connection is tunneled over USB4, with a runtime suspended USB4 host, and firmware implemented connection manager.
Specs state the host must wait 100ms (tU3WakeupRetryDelay) before resending a U3 wake signal if device doesn't respond, leading to U3 -> U0 link transition times around 270ms in the tunneled case.
Cc: stable@vger.kernel.org Fixes: 0200b9f790b0 ("xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0") Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com --- drivers/usb/host/xhci-hub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c index 1e7dc130c39a..f65f1ba2b592 100644 --- a/drivers/usb/host/xhci-hub.c +++ b/drivers/usb/host/xhci-hub.c @@ -1434,7 +1434,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, } spin_unlock_irqrestore(&xhci->lock, flags); if (!wait_for_completion_timeout(&bus_state->u3exit_done[wIndex], - msecs_to_jiffies(100))) + msecs_to_jiffies(500))) xhci_dbg(xhci, "missing U0 port change event for port %d-%d\n", hcd->self.busnum, wIndex + 1); spin_lock_irqsave(&xhci->lock, flags);