[keeping old context since it's been a month...]

On Mon, 2020-05-25 at 12:37 +0300, Mathias Nyman wrote:
> On 21.5.2020 6.45, Rik van Riel wrote:
> > On Wed, 2020-05-20 at 16:34 -0400, Alan Stern wrote:
> > > On Wed, May 20, 2020 at 03:21:44PM -0400, Rik van Riel wrote:
> > > > Interesting. That makes me really curious why things are
> > > > getting stuck, now...
> > > 
> > > This could be a bug in xhci-hcd.  Perhaps the controller's
> > > endpoint 
> > > state needs to be updated after one of these errors
> > > occurs.  Mathias 
> > > will know all about that.
> > 
> > I am seeing something potentially interesting in the
> > giant trace. First the final enqueue/dequeue before
> > the babble error:
> > 
> >           <idle>-0     [005] d.s. 776367.638233: xhci_inc_enq: ISOC
> > 0000000033a6879e: enq 0x0000001014070420(0x0000001014070000) deq
> > 0x0000001014070360(0x0000001014070000) segs 2 stream 0 free_trbs
> > 497
> > bounce 196 cycle 1
> > 
> > The next reference to 0x0000001014070360 is the babble error,
> > and some info on the ISOC buffer itself:
> > 
> >           <idle>-0     [005] d.h. 776367.639187: xhci_handle_event:
> > EVENT: TRB 0000001014070360 status 'Babble Detected' len 196 slot
> > 15 ep
> > 9 type 'Transfer Event' flags e:C
> >           <idle>-0     [005] d.h. 776367.639195:
> > xhci_handle_transfer:
> > ISOC: Buffer 0000000e2676f400 length 196 TD size 0 intr 0 type
> > 'Isoch'
> > flags b:i:I:c:s:I:e:C
> > n
> > Immediately after the babble error, the next request is enqueued,
> > and the doorbell is rung:
> > 
> >           <idle>-0     [005] d.h. 776367.639196: xhci_inc_deq: ISOC
> > 0000000033a6879e: enq 0x0000001014070420(0x0000001014070000) deq
> > 0x0000001014070370(0x0000001014070000) segs 2 stream 0 free_trbs
> > 498 bounce 196 cycle 1
> >           <idle>-0     [005] d.h. 776367.639197: xhci_urb_giveback:
> > ep4in-isoc: urb 0000000072126553 pipe 135040 slot 15 length 196/196
> > sgs 0/0 stream 0 flags 00000206
> >           <idle>-0     [005] d.h. 776367.639197: xhci_inc_deq:
> > EVENT 0000000097f84b16: enq 0x00000010170b5000(0x00000010170b5000)
> > deq 0x00000010170b5670(0x00000010170b5000) segs 1 stream 0
> > free_trbs 254 bounce 0 cycle 1
> >           <idle>-0     [005] ..s. 776367.639212: xhci_urb_enqueue:
> > ep4in-isoc: urb 0000000072126553 pipe 135040 slot 15 length 0/196
> > sgs 0/0 stream 0 flags 00000206
> >           <idle>-0     [005] d.s. 776367.639214: xhci_queue_trb:
> > ISOC: Buffer 0000000e2676f400 length 196 TD size 0 intr 0 type
> > 'Isoch' flags b:i:I:c:s:I:e:c
> >           <idle>-0     [005] d.s. 776367.639214: xhci_inc_enq: ISOC
> > 0000000033a6879e: enq 0x0000001014070430(0x0000001014070000) deq
> > 0x0000001014070370(0x0000001014070000) segs 2 stream 0 free_trbs
> > 497 bounce 196 cycle 1
> >           <idle>-0     [005] d.s. 776367.639215:
> > xhci_ring_ep_doorbell: Ring doorbell for Slot 15 ep4in
> > 
> > However, after that point, no more xhci_handle_transfer: ISOC
> > lines ar seen in the log. The doorbell line above is the last
> > line in the log for ep4in.
> > 
> > Is this some area where USB3 and USB2 behave differently?
> 
> It acts as if the endpoint is no longer running.
> 
> If the endpoint would be halted then
> xhci_requires_manual_halt_cleanup() should
> reset the endpoints and it would show in the traces.
> 
> Could you add the code below and take new traces, it will show the
> endpoint
> state after the Babble error.

Hi Mathias,

I have finally rebooted into a kernel with your tracepoint.
After a babble error, I get the following info in the trace.

[  556.716334] xhci_hcd 0000:00:14.0: Babble error for slot 13 ep 8 on
endpoint

 28672.016 :0/0 xhci-hcd:xhci_handle_tx_event(info: 196609, info2:
12845096, deq: 69501877488, tx_info: 12845252)
 34816.037 :0/0 xhci-hcd:xhci_handle_tx_event(info: 196609, info2:
12845096, deq: 69501877856, tx_info: 12845252)
 38912.043 :0/0 xhci-hcd:xhci_handle_tx_event(info: 196609, info2:
12845096, deq: 69501870176, tx_info: 12845252)

I hope this is useful :)

> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-
> ring.c
> index 0fda0c0f4d31..373d89ef7275 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -2455,6 +2455,7 @@ static int handle_tx_event(struct xhci_hcd
> *xhci,
>  	case COMP_BABBLE_DETECTED_ERROR:
>  		xhci_dbg(xhci, "Babble error for slot %u ep %u on
> endpoint\n",
>  			 slot_id, ep_index);
> +		trace_xhci_handle_tx_event(ep_ctx);
>  		status = -EOVERFLOW;
>  		break;
>  	/* Completion codes for endpoint error state */
> diff --git a/drivers/usb/host/xhci-trace.h b/drivers/usb/host/xhci-
> trace.h
> index b19582b2a72c..5081df079f4a 100644
> --- a/drivers/usb/host/xhci-trace.h
> +++ b/drivers/usb/host/xhci-trace.h
> @@ -360,6 +360,11 @@ DEFINE_EVENT(xhci_log_ep_ctx, xhci_add_endpoint,
>  	TP_ARGS(ctx)
>  );
>  
> +DEFINE_EVENT(xhci_log_ep_ctx, xhci_handle_tx_event,
> +	TP_PROTO(struct xhci_ep_ctx *ctx),
> +	TP_ARGS(ctx)
> +);
> +
>  DECLARE_EVENT_CLASS(xhci_log_slot_ctx,
>  	TP_PROTO(struct xhci_slot_ctx *ctx),
>  	TP_ARGS(ctx),
> 
> 
> 
-- 
All Rights Reversed.