Am Montag, 16. Januar 2006 17:21 schrieb Alan Stern:
> Well, it has happened at last, just as Oliver predicted. A user has a
> Western Digital USB disk drive with an extra HID interface tacked on, the
> drive encounters data transmission errors, and usb-storage skips doing a
> port reset because of the extra interface. As a result, error recovery
> takes a long time (on the order of a minute) and is unreliable. See
>
> http://bugzilla.kernel.org/show_bug.cgi?id=5894
>
> In this case the extra interface didn't matter because it wasn't being
> used. Eventually one will be used, and that means we need a good way to
> reset devices with multiple interfaces.
>
> My idea is to add a new method to struct usb_driver, something like
>
> void (*reset_notify)(struct usb_interface *intf, int after);
>
> The core would call this routine for each interface before the reset with
> after set to 0, and again afterwards with after set to 1. Maybe it would
Using my prophetic powers I declare this interface ugly. If you have
two distinct stages, have two methods.
> skip the interface owned by the driver requesting the reset. Anyway, each
> driver would have a chance to stop whatever it's doing and then
> re-initialize its interface when the reset was complete. In many cases
> the driver could treat it the same as a disconnect followed by a probe.
>
> Drivers with no reset_notify method would have to cope as best they can --
> it won't be a very big problem because there aren't all that many
> composite devices around.
There's a certain danger of getting a reset followed by a secondary reset
as an error treatment, followed by ... Could you do a real disconnect in
theses cases?
Regards
Oliver
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