Re: [RFT PATCH v2] xhci: process isoc TD properly when there was an error mid TD.

[Mathias Nyman <mathias.nyman@linux.intel.com>]

On 19.1.2024 0.16, Michał Pecio wrote:
> My usual set of tests passes:
> - no spam on disconnection from NEC
> - no stream lockup on random errors on NEC
> - no spam on disconnection from VIA
> - finish_td called with right frame->status on VIA
>    (checked by means of extra printks)
> 
>> +		/* Error mid TD, don't give TD back yet */
>> +		td->error_mid_td = true;
>> +		td->urb_length_set = true;
>> +
>> +		frame->actual_length = sum_trb_lengths(xhci, ep->ring, ep_trb) +
>> +			ep_trb_len - remaining;
> Not a problem with this patch, but I noticed that every single use of
> this function ends up adding ep_trb_len, maybe it could be inclusive.
> 
>> +		td->urb->actual_length += frame->actual_length;
> In your first email you mentioned hosts responding to every single TRB,
> perhaps with the same error code repeated each time?
> 
> I imagine it could be problematic here if such hosts really exist and
> if there are enough TRBs to execute this line twice. A check for the
> error_mid_td bit previously set could help, if this is a real risk.

Good point, refactored that code a bit and it now both looks nicer and should
solve this case.

One more patchround

Thanks
Mathias