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Revert "mc146818rtc: fix timer interrupt reinjection"

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This reverts commit b429de7301, except
that the reversal of the outer "if (period)" is left in.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2019-11-17 10:07:38 +01:00
parent 0d074bf8e7
commit 3ae32adff1
1 changed files with 33 additions and 34 deletions
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67
hw/rtc/mc146818rtc.c
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@ -174,7 +174,6 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
int64_t cur_clock, next_irq_clock, lost_clock = 0;
period = rtc_periodic_clock_ticks(s);
if (!period) {
s->irq_coalesced = 0;
timer_del(s->periodic_timer);
@ -197,42 +196,42 @@ periodic_timer_update(RTCState *s, int64_t current_time, uint32_t old_period)
last_periodic_clock = next_periodic_clock - old_period;
lost_clock = cur_clock - last_periodic_clock;
assert(lost_clock >= 0);
}
/*
* s->irq_coalesced can change for two reasons:
*
* a) if one or more periodic timer interrupts have been lost,
* lost_clock will be more that a period.
*
* b) when the period may be reconfigured, we expect the OS to
* treat delayed tick as the new period. So, when switching
* from a shorter to a longer period, scale down the missing,
* because the OS will treat past delayed ticks as longer
* (leftovers are put back into lost_clock). When switching
* to a shorter period, scale up the missing ticks since the
* OS handler will treat past delayed ticks as shorter.
*/
if (s->lost_tick_policy == LOST_TICK_POLICY_SLEW) {
uint32_t old_irq_coalesced = s->irq_coalesced;
/*
* s->irq_coalesced can change for two reasons:
*
* a) if one or more periodic timer interrupts have been lost,
* lost_clock will be more that a period.
*
* b) when the period may be reconfigured, we expect the OS to
* treat delayed tick as the new period. So, when switching
* from a shorter to a longer period, scale down the missing,
* because the OS will treat past delayed ticks as longer
* (leftovers are put back into lost_clock). When switching
* to a shorter period, scale up the missing ticks since the
* OS handler will treat past delayed ticks as shorter.
*/
if (s->lost_tick_policy == LOST_TICK_POLICY_SLEW) {
uint32_t old_irq_coalesced = s->irq_coalesced;
s->period = period;
lost_clock += old_irq_coalesced * old_period;
s->irq_coalesced = lost_clock / s->period;
lost_clock %= s->period;
if (old_irq_coalesced != s->irq_coalesced ||
old_period != s->period) {
DPRINTF_C("cmos: coalesced irqs scaled from %d to %d, "
"period scaled from %d to %d\n", old_irq_coalesced,
s->irq_coalesced, old_period, s->period);
rtc_coalesced_timer_update(s);
}
} else {
/*
* no way to compensate the interrupt if LOST_TICK_POLICY_SLEW
* is not used, we should make the time progress anyway.
*/
lost_clock = MIN(lost_clock, period);
s->period = period;
lost_clock += old_irq_coalesced * old_period;
s->irq_coalesced = lost_clock / s->period;
lost_clock %= s->period;
if (old_irq_coalesced != s->irq_coalesced ||
old_period != s->period) {
DPRINTF_C("cmos: coalesced irqs scaled from %d to %d, "
"period scaled from %d to %d\n", old_irq_coalesced,
s->irq_coalesced, old_period, s->period);
rtc_coalesced_timer_update(s);
}
} else {
/*
* no way to compensate the interrupt if LOST_TICK_POLICY_SLEW
* is not used, we should make the time progress anyway.
*/
lost_clock = MIN(lost_clock, period);
}
assert(lost_clock >= 0 && lost_clock <= period);