Fine.
Though I think this approach will bite us in a different way one day...
Mark Kettenis <mark.kette...@xs4all.nl> wrote:
> While working on suspend/resume for another arm64 board, I ran into an
> issue with xhci(4). We detach USB devices early on in the suspend
> process. At this point we mark the USB bus as "dying" to make sure
> devices don't re-attach. We look at this "dying" flag in the
> interrupt handler and bail out early, before actually acking the
> interrupt. The problem here is that if we actually get an interrupt
> during this phase it will continue to fire, slowing us down or even
> stop us from making progress altogether.
>
> The reason why we bail out early is that we also use the "dying" flag
> for when the xhci(4) controller disappears from under out feet (for
> example when someone removes a USB ExpressCard). In that case we
> don't really want to continue accessing hardware registers that aren't
> there anymore.
>
> I think using the flag for two purposes is a bad idea. The diff below
> introduces another flag that signals that the controller is no longer
> there. This fixes the issue with my arm64 board.
>
> ok?
>
>
> Index: dev/usb/xhci.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/usb/xhci.c,v
> retrieving revision 1.125
> diff -u -p -r1.125 xhci.c
> --- dev/usb/xhci.c 12 Apr 2022 19:41:11 -0000 1.125
> +++ dev/usb/xhci.c 14 Jul 2022 20:20:16 -0000
> @@ -593,7 +593,7 @@ xhci_intr(void *v)
> {
> struct xhci_softc *sc = v;
>
> - if (sc == NULL || sc->sc_bus.dying)
> + if (sc->sc_dead)
> return (0);
>
> /* If we get an interrupt while polling, then just ignore it. */
> @@ -613,6 +613,7 @@ xhci_intr1(struct xhci_softc *sc)
> intrs = XOREAD4(sc, XHCI_USBSTS);
> if (intrs == 0xffffffff) {
> sc->sc_bus.dying = 1;
> + sc->sc_dead = 1;
> return (0);
> }
>
> Index: dev/usb/xhcivar.h
> ===================================================================
> RCS file: /cvs/src/sys/dev/usb/xhcivar.h,v
> retrieving revision 1.12
> diff -u -p -r1.12 xhcivar.h
> --- dev/usb/xhcivar.h 24 Dec 2020 14:11:38 -0000 1.12
> +++ dev/usb/xhcivar.h 14 Jul 2022 20:20:16 -0000
> @@ -88,6 +88,8 @@ struct xhci_softc {
> bus_space_handle_t ioh;
> bus_size_t sc_size;
>
> + int sc_dead;
> +
> bus_size_t sc_oper_off; /* Operational Register space */
> bus_size_t sc_runt_off; /* Runtime */
> bus_size_t sc_door_off; /* Doorbell */
>
