ARM: at91/pit: don't suspend/resume if unused

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]>

---
 arch/arm/mach-at91/at91sam926x_time.c | 8 ++++++++
 1 file changed, 8 insertions(+)

arch/arm/mach-at91/at91sam926x_time.c +8 -0

index e3344b4..44526aa 100644
@@ -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();
 }