On Fri, Dec 04, 2020 at 12:08:39PM -0600, Scott Cheloha wrote:
> On Fri, Dec 04, 2020 at 10:07:07AM +0100, Claudio Jeker wrote:
> > On Thu, Dec 03, 2020 at 10:42:50PM -0600, Scott Cheloha wrote:
> > > Hi,
> > >
> > > mbg(4) is among the few remaining drivers using tsleep(9).
> > >
> > > In a few spots, when the kernel is not cold, the driver will spin for
> > > up to 1/10 seconds waiting for the MBG_BUSY flag to go low.
> > >
> > > We can approximate this behavior by spinning 10 times and sleeping 10
> > > milliseconds each iteration. 10 x 10ms = 100ms = 1/10 seconds.
> > >
> > > I can't test this but I was able to compile it on amd64. It isn't
> > > normally built for amd64, though. Just i386.
> > >
> > > I have my doubts that anyone has this card and is able to actually
> > > test this diff.
> > >
> > > Anybody ok?
> >
> > This code needs to wait for around 70us for the card to process the
> > command (according to the comment). The cold code sleeps a max of
> > 50 * 20us (1ms). I don't see why the regular code should sleep so much
> > longer. I would suggest to use a 1ms timeout and loop 10 times. This is a
> > magnitude more than enough and most probably only one cycle will be
> > needed.
> >
> > IIRC someone got a mbg(4) device some time ago apart from mbalmer@
>
> Makes sense to me. Updated diff attached.
OK claudio@
> How are we going to find this person?
Best way is to commit the diff and wait :)
> Index: mbg.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/mbg.c,v
> retrieving revision 1.31
> diff -u -p -r1.31 mbg.c
> --- mbg.c 29 Nov 2020 03:17:27 -0000 1.31
> +++ mbg.c 4 Dec 2020 18:07:43 -0000
> @@ -417,12 +417,12 @@ mbg_read_amcc_s5920(struct mbg_softc *sc
>
> /* wait for the BUSY flag to go low (approx 70 us on i386) */
> timer = 0;
> - tmax = cold ? 50 : hz / 10;
> + tmax = cold ? 50 : 10;
> do {
> if (cold)
> delay(20);
> else
> - tsleep(tstamp, 0, "mbg", 1);
> + tsleep_nsec(tstamp, 0, "mbg", MSEC_TO_NSEC(1));
> status = bus_space_read_1(sc->sc_iot, sc->sc_ioh,
> AMCC_IMB4 + 3);
> } while ((status & MBG_BUSY) && timer++ < tmax);
> @@ -473,12 +473,12 @@ mbg_read_amcc_s5933(struct mbg_softc *sc
>
> /* wait for the BUSY flag to go low (approx 70 us on i386) */
> timer = 0;
> - tmax = cold ? 50 : hz / 10;
> + tmax = cold ? 50 : 10;
> do {
> if (cold)
> delay(20);
> else
> - tsleep(tstamp, 0, "mbg", 1);
> + tsleep_nsec(tstamp, 0, "mbg", MSEC_TO_NSEC(1));
> status = bus_space_read_1(sc->sc_iot, sc->sc_ioh,
> AMCC_IMB4 + 3);
> } while ((status & MBG_BUSY) && timer++ < tmax);
> @@ -525,12 +525,12 @@ mbg_read_asic(struct mbg_softc *sc, int
>
> /* wait for the BUSY flag to go low */
> timer = 0;
> - tmax = cold ? 50 : hz / 10;
> + tmax = cold ? 50 : 10;
> do {
> if (cold)
> delay(20);
> else
> - tsleep(tstamp, 0, "mbg", 1);
> + tsleep_nsec(tstamp, 0, "mbg", MSEC_TO_NSEC(1));
> status = bus_space_read_1(sc->sc_iot, sc->sc_ioh, ASIC_STATUS);
> } while ((status & MBG_BUSY) && timer++ < tmax);
>
--
:wq Claudio
