[PATCH v9 2/6] clocksource: stm32: increase min delta value
From: Benjamin Gaignard <hidden>
Date: 2017-12-08 11:34:34
Also in:
linux-arm-kernel, lkml
Subsystem:
clocksource, clockevent drivers, the rest · Maintainers:
Daniel Lezcano, Thomas Gleixner, Linus Torvalds
From: Benjamin Gaignard <redacted> 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 <redacted> --- 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);
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2.15.0