From: Sylvain Rochet <[email protected]> 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 <[email protected]> [[email protected]: move to newer clocksource driver] Signed-off-by: Nicolas Ferre <[email protected]> Cc: Daniel Lezcano <[email protected]> --- Hi Sylvain, I re-worked (and "Acked") your patch so it can be applied on the newer Mainline kernels. Beware, I changed the "subject line" as well. The PIT driver moved recently (3.18). Daniel, Can you take this patch in your tree? Thanks, bye. Nicolas. drivers/clocksource/timer-atmel-pit.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/clocksource/timer-atmel-pit.c b/drivers/clocksource/timer-atmel-pit.c index b5b4d4585c9a..5408bc7c68d8 100644 --- a/drivers/clocksource/timer-atmel-pit.c +++ b/drivers/clocksource/timer-atmel-pit.c @@ -123,6 +123,10 @@ static void at91sam926x_pit_suspend(struct clock_event_device *cedev) { struct pit_data *data = clkevt_to_pit_data(cedev); + /* Don't suspend PIT if unused */ + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) + return; + /* Disable timer */ pit_write(data->base, AT91_PIT_MR, 0); } @@ -145,6 +149,10 @@ static void at91sam926x_pit_resume(struct clock_event_device *cedev) { struct pit_data *data = clkevt_to_pit_data(cedev); + /* Don't resume PIT if unused */ + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) + return; + at91sam926x_pit_reset(data); } -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
