On Sun, Feb 26, 2023 at 01:28:04PM +0100, Mark Kettenis wrote:
> > Date: Sun, 26 Feb 2023 18:13:18 +1000
> > From: David Gwynne <da...@gwynne.id.au>
yeesh, i should have proofread my email before i sent it. sorry about
making it harder to read than it should have been.
> > i picked a couple of Dell Wyse 3040 boxes, which are very cute, i
> > like them a lot. however, i have to disable acpitz to be able to
> > use them because the driver gets stuck during attach.
> >
> > during apcitz_attach does a read of all the temperatures. the read
> > of _TMP ends up talking to tipmic(4) via tipmic_thermal_opreg_handler().
> > tipmic_thermal_opreg_handler has a loop on line 335 waiting for
> > sc->sc_stat_adc to change, but that value is only set from tipmic_intr.
> > acpitz_attach is running while the kernel is code, and it appears that
> > the interrupt handler never runs, so that value never changes, and
> > acpitz blocks. also because it's cold, the timeout on the tsleep doesn't
> > do anything. thanks to patrick for helping me on the acpi side of things
> > so we could figure this out.
>
> A better approach might be to make sure that while we're cold,
> tipmic_thermal_opreg_handler() polls for completion. Something like:
>
> while (sc->sc_stat_adc == 0) {
> if (cold) {
> delay(1000);
> tpmic_intr();
> } else {
> if (tsleep(&sc->sc_stat_adc, PRIBIO, "tipmic",
> SEC_TO_NSEC(1))) {
> ...
> }
> }
> }
>
>
> > i tried deferring basically all of acpitz_attach to when kthreads are
> > running, and that works well enough to get to userland.
> >
> > is that reasonable?
>
> The problem is that you can't really know whether AML accesses the
> opregion while cold.
good point. the diff below works in this situation and is less
intrusive.
> > also, shortly after dwiic complains about short reads and the kernel
> > locks up again. i'll have to plug it in and transcribe the exact
> > errors. i think that's a separate problem though.
>
> Yes, dwiic(4) has always been somewhat problematic. Transactions seem
> to fail randomly on some platforms like the atom system you're looking
> at but also on my Ampere eMAG system.
fun. i managed to catch some of the dwiic stuff via dmesg before
it locked up:
dwiic0: timed out waiting for tx_empty intr
dwiic0: timed out waiting for rx_full intr
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x5b
dwiic0: timed out waiting for tx_empty intr
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x01
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x01
dwiic0: timed out waiting for rx_full intr
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x5a
dwiic0: timed out waiting for rx_full intr
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x50
dwiic0: timed out waiting for stop intr
dwiic0: timed out waiting for stop intr
dwiic0: timed out waiting for stop intr
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x01
dwiic0: timed out waiting for bus idle
dwiic0: timed out waiting for stop intr
dwiic0: timed out waiting for stop intr
dwiic0: timed out waiting for stop intr
dwiic0: timed out waiting for stop intr
dwiic0: timed out waiting for stop intr
dwiic0: timed out reading remaining 1
tipmic0: can't read register 0x01
dwiic0: timed out waiting for bus idle
Index: tipmic.c
===================================================================
RCS file: /cvs/src/sys/dev/acpi/tipmic.c,v
retrieving revision 1.7
diff -u -p -r1.7 tipmic.c
--- tipmic.c 6 Apr 2022 18:59:27 -0000 1.7
+++ tipmic.c 26 Feb 2023 23:56:04 -0000
@@ -276,6 +276,25 @@ struct tipmic_regmap tipmic_thermal_regm
{ 0x18, TIPMIC_SYSTEMP_HI, TIPMIC_SYSTEMP_LO }
};
+static int
+tipmic_wait_adc(struct tipmic_softc *sc)
+{
+ int i;
+
+ if (!cold) {
+ return (tsleep_nsec(&sc->sc_stat_adc, PRIBIO, "tipmic",
+ SEC_TO_NSEC(1)));
+ }
+
+ for (i = 0; i < 1000; i++) {
+ delay(1000);
+ if (tipmic_intr(sc) == 1)
+ return (0);
+ }
+
+ return (EWOULDBLOCK);
+}
+
int
tipmic_thermal_opreg_handler(void *cookie, int iodir, uint64_t address,
int size, uint64_t *value)
@@ -333,8 +352,7 @@ tipmic_thermal_opreg_handler(void *cooki
splx(s);
while (sc->sc_stat_adc == 0) {
- if (tsleep_nsec(&sc->sc_stat_adc, PRIBIO, "tipmic",
- SEC_TO_NSEC(1))) {
+ if (tipmic_wait_adc(sc)) {
printf("%s: ADC timeout\n", sc->sc_dev.dv_xname);
break;
}
