On Mon, 2 Nov 2015, Peter Chen wrote:
> Hi Alan,
>
> After a discussion with IC engineer, a brief idea like below:
>
> - Delete the QH from the asynclist directly, Issue the first IAA
> routine, this is we do now.
> - During the first IAA interrupt, judge if asynclistaddr is next address of
> the QH we want to remove, if it does not, issue the second IAA
> routine, else, we consider the controller will not process the removed
> QH any more, so it is safe to remove.
> - If the controller still handles the QH previous than the one we want to
> remove , issue IAA again.
I don't understand this completely. It sounds like you're saying:
Find qh2 such that qh2->qh_next == &qh.
Keep doing IAA interrupts until (asynclistaddr != qh2->qh_dma &&
asynclistaddr != qh->qh_dma).
Is that what you mean? It doesn't sound right. Consider the case
where the async list contains only two QHs: qh2 and qh. Then
asynclistaddr will always point to one or the other.
What about this instead?
Keep doing IAA interrupts until (asynclistaddr != qh->qh_dma).
Then do one more IAA interrupt.
That seems safer.
Alan Stern
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