xhci: Warn when hosts don't halt.

Eric Fu reports a problem with his VIA host controller fetching a zeroed
event ring pointer on resume from suspend.  The host should have been
halted, but we can't be sure because that code ignores the return value
from xhci_halt().  Print a warning when the host controller refuses to
halt within XHCI_MAX_HALT_USEC (currently 16 seconds).

(Update: it turns out that the VIA host controller is reporting a halted
state when it fetches the zeroed event ring pointer.  However, we still
need this warning for other host controllers.)

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index e1963d4..f68bc15 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -106,6 +106,9 @@ int xhci_halt(struct xhci_hcd *xhci)
                        STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
        if (!ret)
                xhci->xhc_state |= XHCI_STATE_HALTED;
+       else
+               xhci_warn(xhci, "Host not halted after %u microseconds.\n",
+                               XHCI_MAX_HALT_USEC);
        return ret;
 }