Ongoing battle with umass(4) and xhci(4)

[Hans Petter Selasky]

> 
> Is there something fishy happening between the USB stack and CAM? hmmm...
>

No,

It is not the CAM layer this time, though there are some bugs there too.


In the beginning of the log I see that in the successful case we receive a 
stall event:

-xhci_check_transfer: slot=1 epno=3 remainder=13 status=6
-xhci_check_transfer: TD is last
-xhci_cmd_stop_ep: 
-xhci_check_command: Received command event
-xhci_configure_reset_endpoint: Could not stop endpoint 3
-xhci_cmd_reset_ep: 
-xhci_check_command: Received command event
-xhci_cmd_set_tr_dequeue_ptr: 
-xhci_check_command: Received command event
-xhci_cmd_evaluate_ctx: 
-xhci_check_command: Received command event
-xhci_cmd_configure_ep: 
-xhci_check_command: Received command event
-xhci_configure_reset_endpoint: Could not configure endpoint 3
-xhci_ep_clear_stall: 
-xhci_device_generic_enter: 
-xhci_setup_generic_chain_sub: NTRB=1
-xhci_setup_generic_chain_sub: LINK=0x82883180
-xhci_setup_generic_chain_sub: NTRB=1
-xhci_setup_generic_chain_sub: LINK=0x82883000
-xhci_setup_generic_chain: first=0xffffff8460883300 last=0xffffff8460883180
-xhci_device_generic_start: 
-xhci_transfer_insert: qh_pos = 1
-xhci_check_transfer: slot=1 epno=1 remainder=0 status=1
-xhci_check_transfer: slot=1 epno=1 remainder=0 status=1
-xhci_check_transfer: Following next TD
-xhci_check_transfer: slot=1 epno=1 remainder=0 status=1
-xhci_check_transfer: slot=1 epno=1 remainder=0 status=1
-xhci_check_transfer: TD is last


This is not received in the failing case.

Maybe this indicates a lost interrupt or something like that?

In /sys/dev/usb/controller/xhci.c

static void
xhci_interrupt_poll(struct xhci_softc *sc)

Add a printf:

                if (i == XHCI_MAX_EVENTS) {
                        i = 0;
                        j ^= 1;

                        /* check for timeout */
                        if (!--t) {
				+			printf("XHCI: Timeout\n");
                                break;
				}
                }


See if what happens.

Also change the xhci.c code to call 

xhci_interrupt_poll() two times instead of one.


--HPS