On Saturday 28 April 2007, Alan Stern wrote:
> On Fri, 27 Apr 2007, Mike Nuss wrote:
> 
> >              So for smaller values of HZ, it would retry for
> > longer. Was this the intended behavior?
> 
> You're right; for some reason I was thinking that the argument to 
> schedule_timeout_interruptible() was in milliseconds, not jiffies.
> 
> I don't know the intended behavior because I didn't write the code.  In 
> principle one would think that retrying for 10 ms or even less would be 
> sufficient, since the SOF interrupt is supposed to occur every 
> millisecond.

I think the intended behavior was to delay long enough to let me
notice and look at the device-under-test to see if it was still
live, before doing anything funky on the host side.  It wasn't
initially as clear that the hardware was flaking out.



> Certainly it's possible.  I don't know what led to the creation of the 
> ZFMicro quirk either, but Dave does.

The person who developed that workaround found that the controller
wasn't restarting properly after unlinks without the delays.  The
OHCI spec doesn't expect them; only that implementation.

Again, the "INTR_SF lossage" has been observed on non-ZFMICRO
implemntations.  Nothing especially "modern" though; it could
be that older OHCI implementations were tuned to expect certain
driver bugs (*cough*microsoft*cough*) that have since been fixed.

- Dave

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