From 103bb56a2831bfc7f2d442da9e47f89f37d34952 Mon Sep 17 00:00:00 2001 From: Daniel Lezcano Date: Mon, 8 Jan 2018 14:28:59 +0100 Subject: [PATCH] clocksource/drivers/stm32: Start the timer's counter sooner As we have a lot of timers on this platform, we can have potentially all the timers enabled in the DT, so we don't want to start the timer for every probe otherwise they will be running for nothing as only one will be used. Start the timer only when setting the mode or when the clocksource is enabled. Tested-by: Benjamin Gaignard Signed-off-by: Daniel Lezcano Acked-by: Benjamin Gaignard Cc: Alexandre Torgue Cc: Linus Torvalds Cc: Maxime Coquelin Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1515418139-23276-20-git-send-email-daniel.lezcano@linaro.org Signed-off-by: Ingo Molnar --- drivers/clocksource/timer-stm32.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/clocksource/timer-stm32.c b/drivers/clocksource/timer-stm32.c index c7d1dae27067..e5cdc3af684c 100644 --- a/drivers/clocksource/timer-stm32.c +++ b/drivers/clocksource/timer-stm32.c @@ -101,7 +101,15 @@ static void stm32_clock_event_disable(struct timer_of *to) writel_relaxed(0, timer_of_base(to) + TIM_DIER); } -static void stm32_clock_event_enable(struct timer_of *to) +/** + * stm32_timer_start - Start the counter without event + * @to: a timer_of structure pointer + * + * Start the timer in order to have the counter reset and start + * incrementing but disable interrupt event when there is a counter + * overflow. By default, the counter direction is used as upcounter. + */ +static void stm32_timer_start(struct timer_of *to) { writel_relaxed(TIM_CR1_UDIS | TIM_CR1_CEN, timer_of_base(to) + TIM_CR1); } @@ -137,7 +145,7 @@ static int stm32_clock_event_set_periodic(struct clock_event_device *clkevt) { struct timer_of *to = to_timer_of(clkevt); - stm32_clock_event_enable(to); + stm32_timer_start(to); return stm32_clock_event_set_next_event(timer_of_period(to), clkevt); } @@ -146,7 +154,7 @@ static int stm32_clock_event_set_oneshot(struct clock_event_device *clkevt) { struct timer_of *to = to_timer_of(clkevt); - stm32_clock_event_enable(to); + stm32_timer_start(to); return 0; } @@ -235,6 +243,13 @@ static int __init stm32_clocksource_init(struct timer_of *to) * sched_clock. */ if (bits == 32 && !stm32_timer_cnt) { + + /* + * Start immediately the counter as we will be using + * it right after. + */ + stm32_timer_start(to); + stm32_timer_cnt = timer_of_base(to) + TIM_CNT; sched_clock_register(stm32_read_sched_clock, bits, timer_of_rate(to)); pr_info("%s: STM32 sched_clock registered\n", name);