Hi,
Wesley Cheng <wcheng@xxxxxxxxxxxxxx> writes:
>> If I understood the whole thing correctly, we want everything except the
>> current request (the one that failed START or UPDATE transfer) to go
>> through giveback(). This really tells me that we're not handling error
>> case in kick_transfer and/or prepare_trbs() correctly.
>>
>
> We don't want the request passed in usb_ep_queue() to be calling
> giveback() IF DONE IN the usb_ep_queue() context only.
right, that's how this should behave.
>> I also don't want to pass another argument to kick_transfer because it
>> should be unnecessary: the current request should *always* be the last
>> one in the list. Therefore we should rely on something like
>> list_last_entry() followed by list_for_each_entry_safe_reverse() to
>> handle this without a special case.
>>
>> ret = dwc3_send_gadget_ep_cmd();
>> if (ret < 0) {
>> current = list_last_entry();
>>
>> unmap(current);
>> for_each_trb_in(current) {
>> clear_HWO(trb);
>> }
>>
>> list_for_entry_safe_reverse() {
>> move_cancelled();
>> }
>> }
>>
> Nice, thanks for the suggestion and info! Problem we have is that kick
> transfer is being used elsewhere, for example, during the TRB complete path:
>
> static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
> const struct dwc3_event_depevt *event, int status)
> {
> ...
> else if (dwc3_gadget_ep_should_continue(dep))
> if (__dwc3_gadget_kick_transfer(dep) == 0)
> no_started_trb = false;
>
> So in these types of calls, we would still want ALL requests to be
> cancelled w/ giveback() called, so that the completion() callbacks can
> cleanup/free those requests accordingly.
>
> If we went and only unmapped the last entry (and removed it from any
> list), then no one would clean it up as it is outside of the
> usb_ep_queue() context, and not within any of the DWC3 lists.
oh, I see what you mean. At the moment we want kick_transfer to behave
in two different manners and that's probably where the bug is
originating from.
It sounds like it's time to split kick_transfer into
kick_queued_transfer() and e.g. continue_pending_transfers()
The thing is that if we continue to sprinkle special cases all over the
place, soon enough it'll be super hard to maintain the driver.
--
balbi
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