On Fri, Jun 07, 2019 at 07:36:36PM -0500, Scott Cheloha wrote:
> [...]
>
> > +
> > +static uint64_t
> > +mcx_timer(struct mcx_softc *sc)
> > +{
> > + uint32_t hi, lo, ni;
> > +
> > + hi = mcx_rd(sc, MCX_INTERNAL_TIMER_H);
> > + for (;;) {
> > + lo = mcx_rd(sc, MCX_INTERNAL_TIMER_L);
> > + mcx_bar(sc, MCX_INTERNAL_TIMER_L, 8, BUS_SPACE_BARRIER_READ);
> > + ni = mcx_rd(sc, MCX_INTERNAL_TIMER_H);
> > +
> > + if (ni == hi)
> > + break;
> > +
> > + hi = ni;
> > + }
> > +
> > + return (((uint64_t)hi << 32) | (uint64_t)lo);
> > }
>
> You could actually truncate this loop:
>
> for (ni = hi + 1; ni != hi; hi = ni) {
> lo = mcx_rd(sc, MCX_INTERNAL_TIMER_L);
> mcx_bar(sc, MCX_INTERNAL_TIMER_L, 8, BUS_SPACE_BARRIER_READ);
> ni = mcx_rd(sc, MCX_INTERNAL_TIMER_H);
> }
>
> but maybe that's too clever :)
this is wrong, ignore this part, your loop is fine.
too clever indeed...
