| Message ID | 1418846023-8581-1-git-send-email-sylvain.rochet@finsecur.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Le 17/12/2014 20:53, Sylvain Rochet a écrit : > Waiting for PIT to stop counting takes a long time: > 1/(Master clock/prescaler/PIVR) > = 1/(133 MHz /16 /2^20) > = 126 ms > > Up to 126 ms if master clock is set to 133 MHz, skipping suspend/resume > of the unused PIT device reduce (suspend time + resume time) from ~140 ms > to ~17 ms. > > Signed-off-by: Sylvain Rochet <sylvain.rochet@finsecur.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> I also moved these changes to the new clocksource PIT driver. Cf. the patch I've just sent titled: (clocksource: timer-atmel-pit: don't suspend/resume if unused) (preserving your authorship of course). Thanks. Bye. > --- > arch/arm/mach-at91/at91sam926x_time.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c > index e3344b4..44526aa 100644 > --- a/arch/arm/mach-at91/at91sam926x_time.c > +++ b/arch/arm/mach-at91/at91sam926x_time.c > @@ -106,6 +106,10 @@ pit_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev) > > static void at91sam926x_pit_suspend(struct clock_event_device *cedev) > { > + /* Don't suspend PIT if unused */ > + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) > + return; > + > /* Disable timer */ > pit_write(AT91_PIT_MR, 0); > } > @@ -125,6 +129,10 @@ static void at91sam926x_pit_reset(void) > > static void at91sam926x_pit_resume(struct clock_event_device *cedev) > { > + /* Don't resume PIT if unused */ > + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) > + return; > + > at91sam926x_pit_reset(); > } > >
diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c index e3344b4..44526aa 100644 --- a/arch/arm/mach-at91/at91sam926x_time.c +++ b/arch/arm/mach-at91/at91sam926x_time.c @@ -106,6 +106,10 @@ pit_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev) static void at91sam926x_pit_suspend(struct clock_event_device *cedev) { + /* Don't suspend PIT if unused */ + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) + return; + /* Disable timer */ pit_write(AT91_PIT_MR, 0); } @@ -125,6 +129,10 @@ static void at91sam926x_pit_reset(void) static void at91sam926x_pit_resume(struct clock_event_device *cedev) { + /* Don't resume PIT if unused */ + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) + return; + at91sam926x_pit_reset(); }
Waiting for PIT to stop counting takes a long time: 1/(Master clock/prescaler/PIVR) = 1/(133 MHz /16 /2^20) = 126 ms Up to 126 ms if master clock is set to 133 MHz, skipping suspend/resume of the unused PIT device reduce (suspend time + resume time) from ~140 ms to ~17 ms. Signed-off-by: Sylvain Rochet <sylvain.rochet@finsecur.com> --- arch/arm/mach-at91/at91sam926x_time.c | 8 ++++++++ 1 file changed, 8 insertions(+)