On Tue, 14 Nov 2006, Romain Liévin wrote:
> Hi Alan,
>
> > It is a bug in the Titanium firmware. In the logs for both handhelds
> you
> > can see where the kernel sends a Set-Interface request after your driver
> releases the interface. (The kernel does this automatically so that the
> interface will be back in its original condition when the next driver
> binds to it.) Both devices return an error, which is a perfectly legal
> response.
> >
> > However the Titanium then crashes. It doesn't respond to the Clear-Halt
> commands sent by the kernel after the Set-Interface fails, whereas the
> TI84+ acknowledges them correctly. Since it has crashed, your driver is
> unable to reconnect and you have to reset the device by unplugging it.
> >
> > The source of the errors is the Titanium failure to respond to the
> kernel's Clear-Halt requests.
>
> I have a burning question: why Linux does not handle this behaviour while
> Windows does not reject it?
Which behavior are you talking about? There are at least two important
things going on here:
1. The kernel sends a Set-Interface request. I don't know why
Windows doesn't do the same thing. Ask somebody at Microsoft.
2. The Titanium crashes. Neither Linux nor Windows can handle
this. Once the device has crashed, all you can do is unplug it.
> Can I handle this 'quirk' directly in my tiusb kernel module or is this
> behaviour managed in the USB core (and thus, not accessible from an upper
> level)? I'm not a USB-internals guru ;-)
The Set-Interface request is sent by the USB core and your driver can't
prevent it; therefore you can't stop the Titanium from crashing.
One thing you _can_ do is to install a firmware update, if any are
available. If that doesn't work out, you can report the problem to Texas
Instruments and ask them to issue an update to fix it.
Alan Stern
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