Author: avg
Date: Fri Oct 25 15:38:09 2019
New Revision: 354076
URL: https://svnweb.freebsd.org/changeset/base/354076
Log:
owc_gpiobus_read_data: compare times in sbintime_t units
Previously the code used sbttous() before microseconds comparison in one
place, sbttons() and nanoseconds in another, division by SBT_1US and
microseconds in yet another.
Now the code consistently uses multiplication by SBT_1US to convert
microseconds to sbintime_t before comparing them with periods between
calls to sbinuptime(). This is fast, this is precise enough (below
0.03%) and the periods defined by the protocol cannot overflow.
Reviewed by: imp (D22108)
MFC after: 2 weeks
Modified:
head/sys/dev/ow/owc_gpiobus.c
Modified: head/sys/dev/ow/owc_gpiobus.c
==============================================================================
--- head/sys/dev/ow/owc_gpiobus.c Fri Oct 25 15:02:50 2019
(r354075)
+++ head/sys/dev/ow/owc_gpiobus.c Fri Oct 25 15:38:09 2019
(r354076)
@@ -296,10 +296,10 @@ owc_gpiobus_read_data(device_t dev, struct ow_timing *
do {
now = sbinuptime();
GETPIN(sc, &sample);
- } while (sbttous(now - then) < t->t_rdv + 2 && sample == 0);
+ } while (now - then < (t->t_rdv + 2) * SBT_1US && sample == 0);
critical_exit();
- if (sbttons(now - then) < t->t_rdv * 1000)
+ if (now - then < t->t_rdv * SBT_1US)
*bit = 1;
else
*bit = 0;
@@ -307,7 +307,7 @@ owc_gpiobus_read_data(device_t dev, struct ow_timing *
/* Wait out the rest of t_slot */
do {
now = sbinuptime();
- } while ((now - then) / SBT_1US < t->t_slot);
+ } while (now - then < t->t_slot * SBT_1US);
RELBUS(sc);
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