Re: [RTF PATCH v3] xhci: process isoc TD properly when there was an error mid TD.

["Michał Pecio" <michal.pecio@gmail.com>]

> Apparently a babble error, and it seems to have generated a "success"
> which the event handler tried to match with the next TD. So a mid TD
> babble may need the same treatment, which is not surprising.

This is now confirmed and fixed here. The change is obvious enough:
        case COMP_ISOCH_BUFFER_OVERRUN:
        case COMP_BABBLE_DETECTED_ERROR:
+               error_mid_td = true;
                frame->status = -EOVERFLOW;
                break;

I don't know yet what COMP_ISOCH_BUFFER_OVERRUN means, but I guess it's
the same story. BTW, error_mid_td is a local variable now and I use the
urb_length_set flag instead, as explained before.

I found that it can be reproduced on the VIA host, with enough tries it
can happen even on a chained TD. NEC doesn't signal these babble errors
but new mid TD event handling should cope with either host.

Debug trace ("interesting" is other than "success" or "short packet"):
[ 4113.376349] xhci_hcd 0000:03:00.0: handle_tx_event interesting ep_trb_dma 132961000 comp_code 3 slot 2 ep 2
[ 4113.376361] xhci_hcd 0000:03:00.0: handle_tx_event first_trb 132961000 last_trb 132961010
[ 4113.376364] xhci_hcd 0000:03:00.0: Error mid isoc TD, wait for final completion event
[ 4113.376366] xhci_hcd 0000:03:00.0: handle_tx_event uninteresting ep_trb_dma 132961010 comp_code 1 slot 2 ep 2
[ 4113.376369] xhci_hcd 0000:03:00.0: handle_tx_event first_trb 132961000 last_trb 132961010
[ 4113.376371] xhci_hcd 0000:03:00.0: Got SUCCESS after mid TD error
[ 4113.376373] xhci_hcd 0000:03:00.0: finish_td comp_code 1 status -75


Thanks,
Michal