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Message-ID: <20190722193456.h4hfte5cczucermd@pengutronix.de>
Date: Mon, 22 Jul 2019 21:34:56 +0200
From: Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>
To: Paul Cercueil <paul@...pouillou.net>
Cc: Thierry Reding <thierry.reding@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>, od@...c.me,
linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] pwm: jz4740: Apply configuration atomically
Hello Paul,
On Fri, Jun 07, 2019 at 05:44:07PM +0200, Paul Cercueil wrote:
> -static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> - int duty_ns, int period_ns)
> +static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + struct pwm_state *state)
> {
> struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
> unsigned long long tmp;
> unsigned long period, duty;
> unsigned int prescaler = 0;
> uint16_t ctrl;
> - bool is_enabled;
>
> - tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
> + tmp = (unsigned long long)clk_get_rate(jz4740->clk) * state->period;
> do_div(tmp, 1000000000);
> period = tmp;
>
> @@ -96,16 +95,14 @@ static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> if (prescaler == 6)
> return -EINVAL;
>
> - tmp = (unsigned long long)period * duty_ns;
> - do_div(tmp, period_ns);
> + tmp = (unsigned long long)period * state->duty_cycle;
> + do_div(tmp, state->period);
> duty = period - tmp;
>
> if (duty >= period)
> duty = period - 1;
>
> - is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
> - if (is_enabled)
> - jz4740_pwm_disable(chip, pwm);
> + jz4740_pwm_disable(chip, pwm);
I assume this stops the PWM. Does this complete the currently running
period? How does the PWM behave then? (Does it still drive the output?
If so, on which level?)
>
> jz4740_timer_set_count(pwm->hwpwm, 0);
> jz4740_timer_set_duty(pwm->hwpwm, duty);
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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