Messages in this thread Patch in this message | | | From | Benjamin Gaignard <> | Subject | [PATCH v9 2/6] clocksource: stm32: increase min delta value | Date | Fri, 8 Dec 2017 12:32:46 +0100 |
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From: Benjamin Gaignard <benjamin.gaignard@linaro.org>
The CPU is a CortexM4 @ 200MHZ and the clocks driving the timers are at 90MHZ with a min delta at 1 you could have an interrupt each 0.01 ms which is really to much. By increase it to 0x60 it give more time (around 1 ms) to CPU to handle the interrupt.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> --- drivers/clocksource/timer-stm32.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/clocksource/timer-stm32.c b/drivers/clocksource/timer-stm32.c index fc61fd18a182..a45f1f1cd040 100644 --- a/drivers/clocksource/timer-stm32.c +++ b/drivers/clocksource/timer-stm32.c @@ -36,6 +36,12 @@ #define TIM_EGR_UG BIT(0) +/* + * The clock driving the hardware is at 90MHZ with a MIN_DELTA + * at 0x60 it gives around 1 ms to the CPU to handle the interrupt + */ +#define MIN_DELTA 0x60 + static int stm32_clock_event_shutdown(struct clock_event_device *evt) { struct timer_of *to = to_timer_of(evt); @@ -129,7 +135,8 @@ static int __init stm32_clockevent_init(struct device_node *node) writel_relaxed(0, timer_of_base(to) + TIM_SR); clockevents_config_and_register(&to->clkevt, - timer_of_period(to), 0x1, max_delta); + timer_of_period(to), + MIN_DELTA, max_delta); pr_info("%pOF: STM32 clockevent driver initialized (%d bits)\n", node, bits); -- 2.15.0
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