1394 bus reset and isochronous transfer.

[Frederic Villeneuve]

Hello,

I'd like to know what happen when a bus reset occurs while an isochrounous
transfer is running ?

According to the SonyDCam sample from the W2K DDK, it looks like resources
need to be freed and reallocated and the isochronous transfer restarted.
But I just tried to generate a bus reset while an isochronous transfer is
running between my computer and a digital camera and it kept running...
I'm running Windows2000 Build 2128.

Thanks for any informations

Best Regards

Frederic Villeneuve

[plan...@my-deja.com]

Hi Frederic,

I can't answer this question from a Windows point of view, as I haven't
done isochronous transfers using Windows yet. However, I can tell you
how it should work at the 1394 level.

Normally on 1394, when before a stream is started, enough bandwidth and
a channel must be reserved for it. When a bus reset occurs, all channel
and bandwidth allocations are automatically freed. However, any node on
the bus sending a stream may continue to send that stream after a bus
reset, and should re-reserve the channel and bandwidth within one second
of the reset.

Therefore, it is correct for the camera to continue sending the stream
after a bus reset. Something on the network must reserve the resources
again, but (hopefully) the stream can continue uninterrupted. Normally,
the application that made the reservations in the first place would do
so again after a reset, although actually it could be done from
anywhere.

Hope this helps,

Peter

In article <s1ca7b...@corp.supernews.com>,

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Peter Lanigan
Consumer Electronics Software Developer
London, UK

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