Re: ehci: fix error handling?

[Julian Coleman <jdc%coris.org.uk@localhost>]

Hi all,

> attach always 'succeeds' in the sense that after attach has been called, 
> detach will always be called. The detach routine should tear down 
> everything that needs tearing down and not do things that will fail. 
> Perhaps the init could simply be done before the attach routine gets the 
> chance to fail?

Some drivers mark the progress through attach so that detach will work
correctly in all cases.  Can we do the same here?  For example, see
sc->sc_att_stage in:

  https://nxr.netbsd.org/xref/src/sys/dev/ic/gem.c

and also how gem_partial_detach() is called when the attach fails part way
through.

Regards,

Julian