linux-kernel - Re: [PATCH v8 11/26] pwm: jz4740: Use regmap and clocks from TCU driver

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Date:   Thu, 13 Dec 2018 15:34:48 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Mathieu Malaterre <malat@...ian.org>,
        Ezequiel Garcia <ezequiel@...labora.co.uk>,
        PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
        linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-clk@...r.kernel.org, od@...c.me
Subject: Re: [PATCH v8 11/26] pwm: jz4740: Use regmap and clocks from TCU
 driver

Hi,

Le jeu. 13 déc. 2018 à 10:30, Uwe Kleine-König 
<u.kleine-koenig@...gutronix.de> a écrit :
> Hello,
> 
> On Wed, Dec 12, 2018 at 11:09:06PM +0100, Paul Cercueil wrote:
>>  [...]
>>   static int jz4740_pwm_enable(struct pwm_chip *chip, struct 
>> pwm_device *pwm)
>>   {
>>  -	uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);
>>  +	struct jz4740_pwm_chip *jz = to_jz4740(chip);
>> 
>>  -	ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
>>  -	jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
>>  -	jz4740_timer_enable(pwm->hwpwm);
>>  +	/* Enable PWM output */
>>  +	regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
>>  +				TCU_TCSR_PWM_EN, TCU_TCSR_PWM_EN);
> 
> Usually follow-up lines are indented to the matching parenthesis.

OK.

>>  [...]
>>   static int jz4740_pwm_config(struct pwm_chip *chip, struct 
>> pwm_device *pwm,
>>   			     int duty_ns, int period_ns)
>>   {
>>   	struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
>>  +	struct clk *clk = jz4740->clks[pwm->hwpwm];
>>  +	unsigned long rate, new_rate, period, duty;
>>   	unsigned long long tmp;
>>  -	unsigned long period, duty;
>>  -	unsigned int prescaler = 0;
>>  -	uint16_t ctrl;
>>  +	unsigned int tcsr;
>>   	bool is_enabled;
>> 
>>  -	tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
>>  -	do_div(tmp, 1000000000);
>>  -	period = tmp;
>>  +	rate = clk_get_rate(clk);
>>  +
>>  +	for (;;) {
>>  +		tmp = (unsigned long long) rate * period_ns;
>>  +		do_div(tmp, 1000000000);
>> 
>>  -	while (period > 0xffff && prescaler < 6) {
>>  -		period >>= 2;
>>  -		++prescaler;
>>  +		if (tmp <= 0xffff)
>>  +			break;
>>  +
>>  +		new_rate = clk_round_rate(clk, rate / 2);
>>  +
>>  +		if (new_rate < rate)
>>  +			rate = new_rate;
>>  +		else
>>  +			return -EINVAL;
>>   	}
>> 
>>  -	if (prescaler == 6)
>>  -		return -EINVAL;
>>  +	clk_set_rate(clk, rate);
> 
> Maybe this could better live in a separate patch. If you split still
> further to have the conversion to regmap in a single patch, then the
> conversion to the clk_* functions and then improve the algorithm for 
> the
> clk settings each of the patches is easier to review than this one 
> patch
> that does all three things at once.

I can try.

> Best regards
> Uwe
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König        
>     |
> Industrial Linux Solutions                 | 
> http://www.pengutronix.de/  |