From: Benedikt Spranger Date: Sat, 6 Mar 2010 17:47:10 +0100 Subject: ARM: AT91: PIT: Remove irq handler when clock event is unused Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.0/patches-4.0.5-rt3.tar.xz Setup and remove the interrupt handler in clock event mode selection. This avoids calling the (shared) interrupt handler when the device is not used. Signed-off-by: Benedikt Spranger Signed-off-by: Thomas Gleixner [bigeasy: redo the patch with NR_IRQS_LEGACY which is probably required since commit 8fe82a55 ("ARM: at91: sparse irq support") which is included since v3.6. Patch based on what Sami Pietikäinen suggested]. Signed-off-by: Sebastian Andrzej Siewior --- arch/arm/mach-at91/at91rm9200_time.c | 1 + drivers/clocksource/timer-atmel-pit.c | 4 ++++ 2 files changed, 5 insertions(+) --- a/arch/arm/mach-at91/at91rm9200_time.c +++ b/arch/arm/mach-at91/at91rm9200_time.c @@ -135,6 +135,7 @@ clkevt32k_mode(enum clock_event_mode mod break; case CLOCK_EVT_MODE_SHUTDOWN: case CLOCK_EVT_MODE_UNUSED: + remove_irq(NR_IRQS_LEGACY + AT91_ID_SYS, &at91rm9200_timer_irq); case CLOCK_EVT_MODE_RESUME: irqmask = 0; break; --- a/drivers/clocksource/timer-atmel-pit.c +++ b/drivers/clocksource/timer-atmel-pit.c @@ -90,6 +90,7 @@ static cycle_t read_pit_clk(struct clock return elapsed; } +static struct irqaction at91sam926x_pit_irq; /* * Clockevent device: interrupts every 1/HZ (== pit_cycles * MCK/16) */ @@ -100,6 +101,8 @@ pit_clkevt_mode(enum clock_event_mode mo switch (mode) { case CLOCK_EVT_MODE_PERIODIC: + /* Set up irq handler */ + setup_irq(at91sam926x_pit_irq.irq, &at91sam926x_pit_irq); /* update clocksource counter */ data->cnt += data->cycle * PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR)); pit_write(data->base, AT91_PIT_MR, @@ -113,6 +116,7 @@ pit_clkevt_mode(enum clock_event_mode mo /* disable irq, leaving the clocksource active */ pit_write(data->base, AT91_PIT_MR, (data->cycle - 1) | AT91_PIT_PITEN); + remove_irq(at91sam926x_pit_irq.irq, &at91sam926x_pit_irq); break; case CLOCK_EVT_MODE_RESUME: break;