On 06/06/2011 08:25 AM, Gerd Hoffmann wrote:
>
> Hi,
>
>>>> -#if EHCI_DEBUG == 0
>>>> - if (qemu_get_clock_ns(vm_clock) / 1000>= ehci->frame_end_usec) {
>>>> - if (async) {
>>>> - DPRINTF("FETCHENTRY: FRAME timer elapsed, exit state
>>>> machine\n");
>>>> - goto out;
>>>> - } else {
>>>> - DPRINTF("FETCHENTRY: WARNING "
>>>> - "- frame timer elapsed during periodic\n");
>>>> - }
>>>> - }
>>>> -#endif
>>
>> This check was added to per Section 4 of the EHCI spec -- the HC should
>> not start transactions that will not be completed before the end of the
>> micro-frame. If you remove this what causes the EHCI model to take a
>> breather?
>
> Look at patch #8. That brings a number of state machine changes. One
> of them is that the async schedule stops as soon as it notices it walks
> in circles (i.e. sees a QH the second time).
>
>>>> - case EST_FETCHENTRY:
>>>> - /* fall through */
>>>
>>> Why drop this case too? As I recall that is needed for proper execution.
>
> The async schedule doesn't pause in fetchentry state any more (also done
> by patch #8).
Ok. see that now.
David
>
> cheers,
> Gerd
>
