Am Dienstag, 24. April 2007 01:32 schrieb Greg KH:
> On Tue, Apr 24, 2007 at 01:24:02AM +0200, Oliver Neukum wrote:
> > Am Dienstag, 24. April 2007 00:35 schrieb Greg KH:
> > > > This suggests that usbfs2 should have special "interface" files as well
> > > > as
> > > > a special "device" file and "endpoint" files.
> > >
> > > Nah, I don't think that will be needed.
> >
> > 1. Interfaces have properties, namely the setting
>
> Yes, which we should be able to control through the control endpoint
> with an ioctl, right?
No, because then we'd have to continue giving access to the whole
device if we want to drive only an interface. The 0 endpoint must be
replicated for each interface, which is in effect the "interface" file
Alan is talking about. Plus, there are situation where some requests
to endpoint 0 must fail and others must work.
> > 2. We cannot operate solely at the level of the endpoint
> > We must know which requests are affected when an interface
> > is affected, eg. reset cannot restore the altsetting. This cannot work
> > at the endpoint level because endpoint 0 is shared. We cannot drop
> > claiming an interface as is done in the current usbfs.
>
> Once you open an endpoint that is not endpoint 0 that would signify that
> the interface is then "claimed" as far as the kernel goes, right?
That's not enough. The kernel must have a notion of _who_ owns the
interface. As a task may own several interfaces, the action must be
explicit. Besides, an interface is not required to have endpoints, nor
should a task be required to open an endpoint just for show.
You are designing a kludge.
Regards
Oliver
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