Re: OHCI hangs after failing to free resources

On Fri, 6 Jul 2007, Mike Nuss wrote:

> On the hardware side though, DI relates to how many frames the HC will
> wait until HccaDoneHead will be updated, and the WDH IRQ isn't sent
> until that happens. But since the TD never gets properly retired by the
> HC when this bug occurs, we never get that interrupt. The last time the
> interrupt would have been sent would have been after the last successful
> completion, would could have been several frames beforehand. So if
> there's only one read endpoint, I don't think this would work, unless
> I'm still missing something.

You're right.

To what extent does the TD get retired?  Did you notice whether the 
NextTransferDescriptor field gets copied into the ED?

Could there be a problem with the DI processing?  Is DI always set to 
0 for your URBs?

If all else fails and you can't get timely interrupts, you can always 
fall back on a kernel timer.  Scan through the data structures once a 
second or thereabouts.  As an optimization, allow the timer to run only 
while there are active URBs.

Alan Stern


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