Author: mav
Date: Tue Aug 16 21:51:29 2011
New Revision: 224919
URL: http://svn.freebsd.org/changeset/base/224919
Log:
Always check current HPET counter value after comparator programming to
avoid lost timer interrupts. Previous optimization attempt doing it only
for intervals less then 5000 ticks (~300us) reported to be unreliable by
some people. Probably because of some heavy SMI code on their boards.
Introduce additional safety interval of 128 counter ticks (~9us) between
programmed comparator and counter values to cover different cases of
delayed write found on some chipsets.
Approved by: re (kib)
Modified:
head/sys/dev/acpica/acpi_hpet.c
head/sys/dev/acpica/acpi_hpet.h
Modified: head/sys/dev/acpica/acpi_hpet.c
==============================================================================
--- head/sys/dev/acpica/acpi_hpet.c Tue Aug 16 21:04:18 2011
(r224918)
+++ head/sys/dev/acpica/acpi_hpet.c Tue Aug 16 21:51:29 2011
(r224919)
@@ -190,13 +190,10 @@ restart:
bus_write_4(sc->mem_res, HPET_TIMER_COMPARATOR(t->num),
t->next);
}
- if (fdiv < 5000) {
- bus_read_4(sc->mem_res, HPET_TIMER_COMPARATOR(t->num));
- now = bus_read_4(sc->mem_res, HPET_MAIN_COUNTER);
- if ((int32_t)(now - t->next) >= 0) {
- fdiv *= 2;
- goto restart;
- }
+ now = bus_read_4(sc->mem_res, HPET_MAIN_COUNTER);
+ if ((int32_t)(now - t->next + HPET_MIN_CYCLES) >= 0) {
+ fdiv *= 2;
+ goto restart;
}
return (0);
}
@@ -679,7 +676,8 @@ hpet_attach(device_t dev)
t->et.et_quality -= 10;
t->et.et_frequency = sc->freq;
t->et.et_min_period.sec = 0;
- t->et.et_min_period.frac = 0x00008000LLU << 32;
+ t->et.et_min_period.frac =
+ (((uint64_t)(HPET_MIN_CYCLES * 2) << 32) / sc->freq) << 32;
t->et.et_max_period.sec = 0xfffffffeLLU / sc->freq;
t->et.et_max_period.frac =
((0xfffffffeLLU << 32) / sc->freq) << 32;
Modified: head/sys/dev/acpica/acpi_hpet.h
==============================================================================
--- head/sys/dev/acpica/acpi_hpet.h Tue Aug 16 21:04:18 2011
(r224918)
+++ head/sys/dev/acpica/acpi_hpet.h Tue Aug 16 21:51:29 2011
(r224919)
@@ -62,4 +62,6 @@
#define HPET_TIMER_FSB_VAL(x) ((x) * 0x20 + 0x110)
#define HPET_TIMER_FSB_ADDR(x) ((x) * 0x20 + 0x114)
+#define HPET_MIN_CYCLES 128 /* Period considered reliable.
*/
+
#endif /* !__ACPI_HPET_H__ */
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