> > I don't recall why the change was never done. Perhaps because of other
> > distractions, or it seemed like it would be too much of a PITA to convert
> > drivers to a two-step init sequence (though I think it could be done in a
> > compatible manner).
>
>
> Possibly because of the "do it in open(2)" rule?
>
> Ignoring the device model entirely, if a driver does a lot of
> talking-to-the-hardware in its probe phase, I consider it buggy, in 2.4
> or 2.5.
>
> The network driver and chardev ones typically follow this rule quite
> well... probe is simple, just registering interfaces with the kernel.
> dev->open is where the driver should (and usually does) power-up the
> hardware, [re-]initialize it, etc.
>
> So each time you come upon a driver that wants dev->driver->start(),
> look closely at the code and wonder why it can't perform the
> dev->driver->start() code in its interface's dev->open member.
Oh, right. Sorry, I should have said 'init()' or 'setup()' rather than
'start()'.
In many drivers there are two discrete operations that happen in the
probe() method: verifying the device can be claimed, and registering the
interfaces. By breaking it into two calls, you can conceptually separate
the actions. It would also give the bus a chance to intercept the call and
perform whatever housekeeping it needed to do at that point, giving James
what he wanted.
However, I don't see a great benefit of doing this, besides making it
_blatantly_ obvious what each call is supposed to do. The driver can call
the bus to perform housekeeping duties during the setup (probe()) period,
and everything should be happy.
-pat
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This archive was generated by hypermail 2b29 : Sat Dec 07 2002 - 22:00:21 EST