[U-Boot] [PATCH] mpc83xx: Make it boot again

[Joakim Tjernlund]

>
> >
> > Timur Tabi wrote:
> > > Wood Scott-B07421 wrote:
> > > > To be totally safe, we probably want to do a readback plus twi (to turn
> > > > a data dependency into a flow dependency) before the isync.
> > >
> > > twi == trap word immediate?
> >
> > Yes.
> >
> > > If so, I don't see how that will turn a data dependency into a flow dependency.
> > > Is that some sort of side effect of twi?
> >
> > It decides based on the input register (data dependency) whether to cause a trap (flow dependency).  We never want it to actually trap, so we set a condition that says never trap, but the dependency is still there -- the hardware doesn't decode it as a no-op.
> >
> > See arch/powerpc/include/asm/io.h, it's used in the I/O read accessors.
>
> Guys, unless you will do the twi stuff now I suggest you ACK this
> patch so 83xx works again.

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