On Thu, Nov 26, 2020 at 08:25:48PM +1100, Jonathan Gray wrote:
> On Tue, Nov 24, 2020 at 07:20:46PM -0600, Scott Cheloha wrote:
> > Hi,
> >
> > Both kettenis@ and mpi@ have mentioned in private that my proposed
> > changes to tsleep_nsec(9) etc. would be nicer if we could just get rid
> > of tsleep(9) etc. entirely.
> >
> > This is difficult, but I'll try.
> >
> > Worst case, we thin out the remaining callers. There are not many
> > left.
> >
> > --
> >
> > So, an(4) is one such caller.
> >
> > In an_wait() we spin for (3 * hz) ticks waiting for CSR_WRITE_2 to
> > return the AN_EV_CMD flag. There is no code handling a case where
> > this fails to happen.
> >
> > What we do in practice is very nearly equivalent to spinning for 3
> > seconds waiting for CSR_WRITE_2 to return the AN_EV_CMD flag, so I
> > have converted it to use tsleep_nsec(9).
> >
> > This compiles on amd64 but I can't test it.
> >
> > Thoughts? ok?
>
> I don't see why the upper bound would have to be so precise.
>
> Why not just
>
> for (i = 0; i < 3000; i += 100) {
> if (CSR_READ_2(sc, AN_EVENT_STAT) & AN_EV_CMD)
> break;
> tsleep_nsec(sc, PWAIT, "anatch", MSEC_TO_NSEC(100));
> }
>
Agreed, that seems more in the spirit of such wait loops.
> >
> > Index: an.c
> > ===================================================================
> > RCS file: /cvs/src/sys/dev/ic/an.c,v
> > retrieving revision 1.76
> > diff -u -p -r1.76 an.c
> > --- an.c 10 Jul 2020 13:26:37 -0000 1.76
> > +++ an.c 25 Nov 2020 01:19:16 -0000
> > @@ -678,13 +678,18 @@ an_linkstat_intr(struct an_softc *sc)
> > void
> > an_wait(struct an_softc *sc)
> > {
> > - int i;
> > + struct timespec now, end;
> > +
> > + nanouptime(&now);
> > + end = now;
> > + end.tv_sec += 3; /* spin for at most three seconds */
> >
> > CSR_WRITE_2(sc, AN_COMMAND, AN_CMD_NOOP2);
> > - for (i = 0; i < 3*hz; i++) {
> > - if (CSR_READ_2(sc, AN_EVENT_STAT) & AN_EV_CMD)
> > + while ((CSR_READ_2(sc, AN_EVENT_STAT) & AN_EV_CMD) == 0) {
> > + nanouptime(&now);
> > + if (timespeccmp(&end, &now, <=))
> > break;
> > - (void)tsleep(sc, PWAIT, "anatch", 1);
> > + tsleep_nsec(sc, PWAIT, "anatch", MSEC_TO_NSEC(10));
> > }
> > CSR_WRITE_2(sc, AN_EVENT_ACK, AN_EV_CMD);
> > }
> >
> >
>
--
:wq Claudio
