Question about pipes and ugen

[Julian Elischer]

M. Warner Losh wrote:

>In message: <41B0C118.8070001 at elischer.org>
>            Julian Elischer <julian at elischer.org> writes:
>: I didn't say stack.. I said libusb (excepty I spelled it usblib)
>
>OK.  I got confused...
>
>: it recovers on several machines where FreeBSD looses communications with 
>: the target after an error.
>
>Hmmmm.  Actually, FreeBSD does do the ClearFeature(Halt) on opening of
>pipes by the driver (which ugen does each time the pipe subdevice is
>opened).  ClearFeature(Stall) was unfortunately typed from memory
>rather than looking at the standard (section 9.4.5).  What were you
>thinking about chaning in this area?
>
Well for start implementing the call in libusb so it matches linux :-)
It's a stub in the freeBSD version.

Then it is possible that on an endpoint after it has timed out,
you sholdl do a "Get Status" on the endpoint to check if it is in halt
state and if it is then clear it.
( see section 9.4.5 of the usb-2 spec) (page 254)


believe it or not we are using a device that gets in this state pretty 
easily and
**Doesn't respond to a USB reset**  but for some reason it does respond 
to a ClearFeature(halt)
on the endpoint.  (I'd like to get my hands on the idiots that decided 
to make "reset"
not work on that device.


>Warner
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