[PATCH] powerpc: Cell timebase bug workaround

Stephen Rothwell sfr at canb.auug.org.au
Mon Oct 9 18:36:52 EST 2006

On Mon, 09 Oct 2006 17:05:17 +1000 Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
> > Why not branch back to the mftb if the lower word is zero (this would
> > also take care of the very unlikely "hitting the bug more than once" case
> > and the "normal" case would then not have to branch at all.  (And it uses
> > one less instruction.)
> Because that would cause us to spinloop for the whole duration of a tb
> tick in that case, which is pretty bad when the timebase is slow (the
> slower I've seen so far is 14Mhz).

Right!  /me hits himself in the forehead :-)

Stephen Rothwell                    sfr at canb.auug.org.au
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