| Message ID | 20190618140358.13148-8-digetx@gmail.com |
|---|---|
| State | Deferred |
| Headers | show |
| Series | Few more cleanups for tegra-timer | expand |
On 18/06/2019 15:03, Dmitry Osipenko wrote: > Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after > one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks > are defined by clockevents_config_and_register(min, max) invocation and > the min value is set to 1 tick. Hence "cycles" value can't ever be 0, > unless it's a bug in clocksource core. > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- > drivers/clocksource/timer-tegra.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c > index 2673b6e0caa8..b84324288749 100644 > --- a/drivers/clocksource/timer-tegra.c > +++ b/drivers/clocksource/timer-tegra.c > @@ -54,9 +54,16 @@ static int tegra_timer_set_next_event(unsigned long cycles, > { > void __iomem *reg_base = timer_of_base(to_timer_of(evt)); > > - writel_relaxed(TIMER_PTV_EN | > - ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */ > - reg_base + TIMER_PTV); > + /* > + * Tegra's timer uses n+1 scheme for the counter, i.e. timer will > + * fire after one tick if 0 is loaded. > + * > + * The minimum and maximum numbers of oneshot ticks are defined > + * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation > + * below in the code. Hence the cycles (ticks) can't be outside of > + * a range supportable by hardware. > + */ > + writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV); > > return 0; > } > Acked-by: Jon Hunter <jonathanh@nvidia.com> Cheers Jon
On Tue, Jun 18, 2019 at 05:03:57PM +0300, Dmitry Osipenko wrote: > Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after > one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks > are defined by clockevents_config_and_register(min, max) invocation and > the min value is set to 1 tick. Hence "cycles" value can't ever be 0, > unless it's a bug in clocksource core. > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- > drivers/clocksource/timer-tegra.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) Acked-by: Thierry Reding <treding@nvidia.com>
19.06.2019 11:19, Thierry Reding пишет: > On Tue, Jun 18, 2019 at 05:03:57PM +0300, Dmitry Osipenko wrote: >> Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after >> one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks >> are defined by clockevents_config_and_register(min, max) invocation and >> the min value is set to 1 tick. Hence "cycles" value can't ever be 0, >> unless it's a bug in clocksource core. >> >> Signed-off-by: Dmitry Osipenko <digetx@gmail.com> >> --- >> drivers/clocksource/timer-tegra.c | 13 ++++++++++--- >> 1 file changed, 10 insertions(+), 3 deletions(-) > > Acked-by: Thierry Reding <treding@nvidia.com> > Thanks!
diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c index 2673b6e0caa8..b84324288749 100644 --- a/drivers/clocksource/timer-tegra.c +++ b/drivers/clocksource/timer-tegra.c @@ -54,9 +54,16 @@ static int tegra_timer_set_next_event(unsigned long cycles, { void __iomem *reg_base = timer_of_base(to_timer_of(evt)); - writel_relaxed(TIMER_PTV_EN | - ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */ - reg_base + TIMER_PTV); + /* + * Tegra's timer uses n+1 scheme for the counter, i.e. timer will + * fire after one tick if 0 is loaded. + * + * The minimum and maximum numbers of oneshot ticks are defined + * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation + * below in the code. Hence the cycles (ticks) can't be outside of + * a range supportable by hardware. + */ + writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV); return 0; }
Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks are defined by clockevents_config_and_register(min, max) invocation and the min value is set to 1 tick. Hence "cycles" value can't ever be 0, unless it's a bug in clocksource core. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- drivers/clocksource/timer-tegra.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)