| Message ID | 9fb47bb0f1355221ef074766d5cc49f2de97e79b.1453402860.git.digetx@gmail.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Jan 21, 2016 at 11:03 AM, Dmitry Osipenko <digetx@gmail.com> wrote: > ptimer_get_count() might be called while QEMU timer already been expired. > In that case ptimer would return counter = 0, which might be undesirable > in case of polled timer. Do counter wrap around for periodic timer to keep > it distributed. In order to achieve more accurate emulation behaviour of > certain hardware, don't perform wrap around when in icount mode and return > counter = 0 in that case (that doesn't affect polled counter distribution). > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com> > --- > hw/core/ptimer.c | 19 +++++++++++++------ > 1 file changed, 13 insertions(+), 6 deletions(-) > > diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c > index 6dc1677..cb50d30 100644 > --- a/hw/core/ptimer.c > +++ b/hw/core/ptimer.c > @@ -83,14 +83,16 @@ static void ptimer_tick(void *opaque) > > uint64_t ptimer_get_count(ptimer_state *s) > { > - int64_t now; > uint64_t counter; > > if (s->enabled) { > - now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); > + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); > + int64_t next = s->next_event; > + bool expired = (now - next >= 0); > + bool oneshot = (s->enabled == 2); > + > /* Figure out the current counter value. */ > - if (now - s->next_event > 0 > - || s->period == 0) { > + if (s->period == 0 || (expired && (oneshot || use_icount))) { > /* Prevent timer underflowing if it should already have > triggered. */ > counter = 0; > @@ -102,7 +104,7 @@ uint64_t ptimer_get_count(ptimer_state *s) > uint32_t period_frac = s->period_frac; > uint64_t period = s->period; > > - if ((s->enabled == 1) && !use_icount && (s->delta * period < 10000)) { > + if (!oneshot && (s->delta * period < 10000) && !use_icount) { > period = 10000 / s->delta; > period_frac = 0; > } > @@ -117,7 +119,7 @@ uint64_t ptimer_get_count(ptimer_state *s) > backwards. > */ > > - rem = s->next_event - now; > + rem = expired ? now - next : next - now; > div = period; > > clz1 = clz64(rem); > @@ -137,6 +139,11 @@ uint64_t ptimer_get_count(ptimer_state *s) > div += 1; > } > counter = rem / div; > + > + if (expired && (counter != 0)) { > + /* Wrap around periodic counter. */ > + counter = s->limit - counter % s->limit; > + } > } > } else { > counter = s->delta; > -- > 2.7.0 >
Hello Peter, 24.01.2016 08:29, Peter Crosthwaite пишет: [snip] >> + if (expired && (counter != 0)) { >> + /* Wrap around periodic counter. */ >> + counter = s->limit - counter % s->limit; >> + } Noticed another nit here. This should be: counter = s->limit - (counter - 1) % s->limit; So wraparound for counter = -1 is counter = limit (not limit - 1). Will fix it in V12. I suppose your r-b is still valid, otherwise please let me know.
diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c index 6dc1677..cb50d30 100644 --- a/hw/core/ptimer.c +++ b/hw/core/ptimer.c @@ -83,14 +83,16 @@ static void ptimer_tick(void *opaque) uint64_t ptimer_get_count(ptimer_state *s) { - int64_t now; uint64_t counter; if (s->enabled) { - now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + int64_t next = s->next_event; + bool expired = (now - next >= 0); + bool oneshot = (s->enabled == 2); + /* Figure out the current counter value. */ - if (now - s->next_event > 0 - || s->period == 0) { + if (s->period == 0 || (expired && (oneshot || use_icount))) { /* Prevent timer underflowing if it should already have triggered. */ counter = 0; @@ -102,7 +104,7 @@ uint64_t ptimer_get_count(ptimer_state *s) uint32_t period_frac = s->period_frac; uint64_t period = s->period; - if ((s->enabled == 1) && !use_icount && (s->delta * period < 10000)) { + if (!oneshot && (s->delta * period < 10000) && !use_icount) { period = 10000 / s->delta; period_frac = 0; } @@ -117,7 +119,7 @@ uint64_t ptimer_get_count(ptimer_state *s) backwards. */ - rem = s->next_event - now; + rem = expired ? now - next : next - now; div = period; clz1 = clz64(rem); @@ -137,6 +139,11 @@ uint64_t ptimer_get_count(ptimer_state *s) div += 1; } counter = rem / div; + + if (expired && (counter != 0)) { + /* Wrap around periodic counter. */ + counter = s->limit - counter % s->limit; + } } } else { counter = s->delta;
ptimer_get_count() might be called while QEMU timer already been expired. In that case ptimer would return counter = 0, which might be undesirable in case of polled timer. Do counter wrap around for periodic timer to keep it distributed. In order to achieve more accurate emulation behaviour of certain hardware, don't perform wrap around when in icount mode and return counter = 0 in that case (that doesn't affect polled counter distribution). Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- hw/core/ptimer.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)