usbd config file parse behaviour

[Bernd Walter]

On Tue, Mar 30, 2004 at 01:46:32AM -0700, M. Warner Losh wrote:
> In message: <20040330083607.GC32646 at cicely12.cicely.de>
>             Bernd Walter <ticso at cicely12.cicely.de> writes:
> : On Mon, Mar 29, 2004 at 07:44:34PM -0700, M. Warner Losh wrote:
> : > In message: <1080613926.1125.6.camel at dirk>
> : >             Sam Lawrance <samuel.lawrance at studentmail.newcastle.edu.au> writes:
> : > : On Sun, 2004-03-28 at 20:47, Bernd Walter wrote:
> : > : > On Sun, Mar 28, 2004 at 01:31:03AM -0700, M. Warner Losh wrote:
> : > : > > Btw, any interest in making it possible to kldload a usb module and
> : > : > > having device attach to it?  Right now the usb code assumes that you
> : > : > > can unplug the device and replug it back in.  I have at least two
> : > : > > devices on my laptop that can't be removed (bluetooth and memory stick
> : > : > > reader), so I can't dynamically load drivers for them...
> : > : > 
> : > : > I'll think about it.
> : > : > Reprobing is not so much an issue as selecting an interface for it.
> : > : 
> : > : would this done by filling in uhub_driver_added() to find a better
> : > : driver match for a device and reattaching?
> : > 
> : > Yes.  Actually, it also requires some changes to newbus as well to
> : > allow for rebidding of devices.  And there's some minor resetting of
> : > the device that likely needs to happen, but that's lower priority.
> : 
> : Don't forget that we already have a driver for every USB device: ugen(4)
> : We need a better trigger to reprobe drivers - thats the real problem.
> 
> No.  That's not the real problem here.  The real problem here is that
> uhub doesn't implement the driver_added callback correctly.  The ugen
> issue, while interesting, can be overcome by not having ugen in the
> kernel.

Not having ugen in the kernel is not an option.
I can't say that I really like the problems introduced by ugen, but
since I have no better idea and ugen is widely used - even by me.

> When ugen is in the kernel, we do need to do the rebid thing in
> newbus, which we don't do, but there's little point in fixing one w/o
> fixing the other.

You can't kldload a new driver and reshuffeling all ugen instances.
They are possibly used and probing for USB devices requires exclusive
access in many cases.

I'm more thinking about some kind of userland tool that allows
retriggering an USB device in a controlled way.
Such a feature is required for some types of firmware downloaders too.
Intelligent USB chips requireing firmware download could disconneect
and reconnect themself from the bus e.g. the TI-TUSB* family, but
there are still others in the wild.
I've seen firmware downloaders to do evil things as reseting an USB
ports on their own, which is quite dangerously as it introduces a
race for having multiple devices with address 0 (the default for
freshly attached ones).

-- 
B.Walter                   BWCT                http://www.bwct.de
ticso at bwct.de                                  info at bwct.de