From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Gaignard Subject: [PATCH v9 2/6] clocksource: stm32: increase min delta value Date: Fri, 8 Dec 2017 12:32:46 +0100 Message-ID: <20171208113250.359-3-benjamin.gaignard@st.com> References: <20171208113250.359-1-benjamin.gaignard@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171208113250.359-1-benjamin.gaignard@st.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: robh+dt@kernel.org, mark.rutland@arm.com, linux@armlinux.org.uk, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, daniel.lezcano@linaro.org, tglx@linutronix.de, arnd@arndb.de Cc: devicetree@vger.kernel.org, Benjamin Gaignard , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org From: Benjamin Gaignard 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 --- 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