linux-kernel - Re: [PATCH v2 3/6] clocksource/drivers/tegra: Set and use timer's period

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Message-ID: <ac8a1da8-9b82-3d5a-5fa6-0c1cc7f627f1@nvidia.com>
Date:   Fri, 14 Jun 2019 16:48:32 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Joseph Lo <josephl@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>
CC:     <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/6] clocksource/drivers/tegra: Set and use timer's
 period


On 10/06/2019 17:43, Dmitry Osipenko wrote:
> The of_clk structure has a period field that is set up initially by
> timer_of_clk_init(), that period value need to be adjusted for a case of
> TIMER1-9 that are running at a fixed rate that doesn't match the clock's
> rate. Note that the period value is currently used only by some of the
> clocksource drivers internally and hence this is just a minor cleanup
> change that doesn't fix anything.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/clocksource/timer-tegra.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
> index 810b4e7435cf..646b3530c2d2 100644
> --- a/drivers/clocksource/timer-tegra.c
> +++ b/drivers/clocksource/timer-tegra.c
> @@ -71,9 +71,9 @@ static int tegra_timer_shutdown(struct clock_event_device *evt)
>  static int tegra_timer_set_periodic(struct clock_event_device *evt)
>  {
>  	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
> +	unsigned long period = timer_of_period(to_timer_of(evt));
>  
> -	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER |
> -		       ((timer_of_rate(to_timer_of(evt)) / HZ) - 1),
> +	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1),
>  		       reg_base + TIMER_PTV);
>  
>  	return 0;
> @@ -297,6 +297,7 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
>  		cpu_to->clkevt.rating = rating;
>  		cpu_to->clkevt.cpumask = cpumask_of(cpu);
>  		cpu_to->of_base.base = timer_reg_base + base;
> +		cpu_to->of_clk.period = DIV_ROUND_UP(rate, HZ);

Any reason you made this a round-up?

Jon

-- 
nvpublic