Re: CVS commit: src/sys/dev/ic

[Tobias Nygren <tnn%NetBSD.org@localhost>]

> > I wonder, does the device need the read, or is the bus_space_barrier()
> > insufficient to flush the write to the device?
> 
> I thave no idea. It works without the read on some machines - might be  
> a quirk in the Blade 2500's hardware. Either way we can probably get  
> rid of the bus_space_barrier().

IIRC the pcf8584 has a timing constraint on consecutive bus writes.
Something like 5 clocks minimum delay at 10MHz. The dummy read may be a
sun-devised way to ensure this constraint is met (I don't think the
ebus hardware enforces it).