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