Acknowledge xhci(4) interrupts before calling usb_schedsoftintr().

On powerdown (halt -p), sd(4)'s suspend function tries to powerdown
a USB mass storage using a STOP command.  In that case we are already
cold and splhigh(), so that the xhci is supposed to run in polling-
mode.

usb_schedsoftintr() behaves differently when running in polling-mode.
Instead of scheduling a soft interrupt, it immediately dequeues from
the event queue.  But dequeueing means touching the xhci registers.

Apparently we need to acknowledge the interrupts before touching those
registers, the hardware doesn't like it otherwise and we will never get
an interrupt status for the second transfer.

ok gerhard@

1 files changed, 5 insertions, 5 deletions

diff --git a/sys/dev/usb/xhci.c b/sys/dev/usb/xhci.c
index 2d65208f3db..903e57039a0 100644
--- a/sys/dev/usb/xhci.c
+++ b/sys/dev/usb/xhci.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: xhci.c,v 1.114 2020/04/03 20:11:47 patrick Exp $ */
+/* $OpenBSD: xhci.c,v 1.115 2020/06/24 09:43:20 patrick Exp $ */
 
 /*
  * Copyright (c) 2014-2015 Martin Pieuchot
@@ -624,13 +624,13 @@ xhci_intr1(struct xhci_softc *sc)
 		return (1);
 	}
 
-	XOWRITE4(sc, XHCI_USBSTS, intrs); /* Acknowledge */
-	usb_schedsoftintr(&sc->sc_bus);
-
-	/* Acknowledge PCI interrupt */
+	/* Acknowledge interrupts */
+	XOWRITE4(sc, XHCI_USBSTS, intrs);
 	intrs = XRREAD4(sc, XHCI_IMAN(0));
 	XRWRITE4(sc, XHCI_IMAN(0), intrs | XHCI_IMAN_INTR_PEND);
 
+	usb_schedsoftintr(&sc->sc_bus);
+
 	return (1);
 }