On Thu, 18 Mar 2004, Alan Stern wrote:

> > Are you sure that's what's making it happen?  Or is your
> > software maybe trying to set the configuration?  That would
> > get rid of the old devices, and create new ones.
> 
> Something definitely is setting the configuration.  The interface 
> registration events are in the system log.

We're getting somewhere: I replaced /sbin/hotplug by /bin/true and have
successfully scanned a 47 MB PPM file with iscan under 2.6 - something
that would consistently fail previously.

> > Software that tries to change the device configuration would
> > certainly cause lots of hotplugging.  Basically that's a bad
> > idea.  There's a call to just _reset_ the configuration, that
> > verges on reasonable ... for devices that only have a single
> > driver on the device interfaces.
> 
> That's part of the problem.  Another part is that whatever program is 
> running as the hotplug agent is using timeouts of 0.1 seconds to read the 
> device and configuration descriptors.  It should be using something more 
> like 5 seconds.

Some questions:

1. Should configuration changes be locked out while bulk transfers are
   in progress?

2. Leaving configuration issues aside, another difference in hardware is
   that the VIA KT133 (82C686A) I had no troubles supported USB 1.1
   only, whereas the KT600 (8237) also supports USB 2.0, hence EHCI. I
   don't know about these companionships between EHCI and UHCI ports -
   are the ports virtually "handed over" between EHCI and UHCI depending
   on whether the bus talks 1.5, 12 or 480 Mbit/s?

2b. Or might speed negotiations/switches cause hotplug events in 2.6?

-- 
Matthias Andree

Encrypt your mail: my GnuPG key ID is 0x052E7D95


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