The third parameter(u64 start_tstamp) of timecounter_init() should
be the start time by ns, not a cycle counter.
Signed-off-by: Xiubo Li <[email protected]>
---
drivers/clocksource/arm_arch_timer.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5163ec1..6c3cfd8 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -426,7 +426,7 @@ struct timecounter *arch_timer_get_timecounter(void)
static void __init arch_counter_register(unsigned type)
{
- u64 start_count;
+ u64 start_count, start_ns;
/* Register the CP15 based counter if we have one */
if (type & ARCH_CP15_TIMER)
@@ -438,7 +438,8 @@ static void __init arch_counter_register(unsigned type)
clocksource_register_hz(&clocksource_counter, arch_timer_rate);
cyclecounter.mult = clocksource_counter.mult;
cyclecounter.shift = clocksource_counter.shift;
- timecounter_init(&timecounter, &cyclecounter, start_count);
+ start_ns = cyclecounter_cyc2ns(&cyclecounter, start_count);
+ timecounter_init(&timecounter, &cyclecounter, start_ns);
/* 56 bits minimum, so we assume worst case rollover */
sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
--
1.8.5
On 06/11/14 01:37, Xiubo Li wrote:
> The third parameter(u64 start_tstamp) of timecounter_init() should
> be the start time by ns, not a cycle counter.
>
> Signed-off-by: Xiubo Li <[email protected]>
> ---
> drivers/clocksource/arm_arch_timer.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 5163ec1..6c3cfd8 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -426,7 +426,7 @@ struct timecounter *arch_timer_get_timecounter(void)
>
> static void __init arch_counter_register(unsigned type)
> {
> - u64 start_count;
> + u64 start_count, start_ns;
>
> /* Register the CP15 based counter if we have one */
> if (type & ARCH_CP15_TIMER)
> @@ -438,7 +438,8 @@ static void __init arch_counter_register(unsigned type)
> clocksource_register_hz(&clocksource_counter, arch_timer_rate);
> cyclecounter.mult = clocksource_counter.mult;
> cyclecounter.shift = clocksource_counter.shift;
> - timecounter_init(&timecounter, &cyclecounter, start_count);
> + start_ns = cyclecounter_cyc2ns(&cyclecounter, start_count);
> + timecounter_init(&timecounter, &cyclecounter, start_ns);
>
> /* 56 bits minimum, so we assume worst case rollover */
> sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
This doesn't make much sense. We're converting start_count, which could
be a very large number, into nanoseconds. It looks like we're assuming
the counter always starts at 0 which is not always true if you sit in a
bootloader for a long time. Perhaps it would be better to just do
timecounter_init(&timecounter, &cyclecounter, 0);
or
timecounter_init(&timecounter, &cyclecounter,
ktime_to_ns(ktime_get_real()));
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
> > drivers/clocksource/arm_arch_timer.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/clocksource/arm_arch_timer.c
> b/drivers/clocksource/arm_arch_timer.c
> > index 5163ec1..6c3cfd8 100644
> > --- a/drivers/clocksource/arm_arch_timer.c
> > +++ b/drivers/clocksource/arm_arch_timer.c
> > @@ -426,7 +426,7 @@ struct timecounter *arch_timer_get_timecounter(void)
> >
> > static void __init arch_counter_register(unsigned type)
> > {
> > - u64 start_count;
> > + u64 start_count, start_ns;
> >
> > /* Register the CP15 based counter if we have one */
> > if (type & ARCH_CP15_TIMER)
> > @@ -438,7 +438,8 @@ static void __init arch_counter_register(unsigned type)
> > clocksource_register_hz(&clocksource_counter, arch_timer_rate);
> > cyclecounter.mult = clocksource_counter.mult;
> > cyclecounter.shift = clocksource_counter.shift;
> > - timecounter_init(&timecounter, &cyclecounter, start_count);
> > + start_ns = cyclecounter_cyc2ns(&cyclecounter, start_count);
> > + timecounter_init(&timecounter, &cyclecounter, start_ns);
> >
> > /* 56 bits minimum, so we assume worst case rollover */
> > sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
>
> This doesn't make much sense. We're converting start_count, which could
> be a very large number, into nanoseconds. It looks like we're assuming
> the counter always starts at 0 which is not always true if you sit in a
> bootloader for a long time.
Yes, the counter here may usually start counting at bootloader time from zero.
> Perhaps it would be better to just do
>
> timecounter_init(&timecounter, &cyclecounter, 0);
>
> or
>
> timecounter_init(&timecounter, &cyclecounter,
> ktime_to_ns(ktime_get_real()));
>
Here the ktime_get_real() will always return 0, before setting the system clock,
Like:
"rtc-ds3232 1-0068: setting system clock to 2014-06-12 13:01:24 UTC (1402578084)"
And if so, why not just set it to 0 ? And by the way, 0 is must here ?
Thanks,
BRs
Xiubo
On 06/12/14 00:45, [email protected] wrote:
>
> And if so, why not just set it to 0 ? And by the way, 0 is must here ?
>
>
I would just set it to 0 and be done with it. But all of this doesn't
seem very urgent. The only user of this timecounter is using it for the
read() and mult/shift members. We never call timecounter_read() or
timecounter_cyc2time() so the nsec member is irrelevant.
--
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hosted by The Linux Foundation