linux-kernel - Re: [PATCH v14 04/10] pwm: max7360: Add MAX7360 PWM support

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Message-Id: <DCQT3UNG2Y41.2V411GFLLDVEP@bootlin.com>
Date: Fri, 12 Sep 2025 14:05:24 +0200
From: "Mathieu Dubois-Briand" <mathieu.dubois-briand@...tlin.com>
To: Uwe Kleine-König <ukleinek@...nel.org>
Cc: "Lee Jones" <lee@...nel.org>, "Rob Herring" <robh@...nel.org>,
 "Krzysztof Kozlowski" <krzk+dt@...nel.org>, "Conor Dooley"
 <conor+dt@...nel.org>, "Kamel Bouhara" <kamel.bouhara@...tlin.com>, "Linus
 Walleij" <linus.walleij@...aro.org>, "Bartosz Golaszewski" <brgl@...ev.pl>,
 "Dmitry Torokhov" <dmitry.torokhov@...il.com>, "Michael Walle"
 <mwalle@...nel.org>, "Mark Brown" <broonie@...nel.org>, "Greg
 Kroah-Hartman" <gregkh@...uxfoundation.org>, "Rafael J. Wysocki"
 <rafael@...nel.org>, "Danilo Krummrich" <dakr@...nel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-gpio@...r.kernel.org>, <linux-input@...r.kernel.org>,
 <linux-pwm@...r.kernel.org>, <andriy.shevchenko@...el.com>,
 Grégory Clement <gregory.clement@...tlin.com>, "Thomas
 Petazzoni" <thomas.petazzoni@...tlin.com>, "Andy Shevchenko"
 <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v14 04/10] pwm: max7360: Add MAX7360 PWM support

On Fri Sep 12, 2025 at 10:57 AM CEST, Uwe Kleine-König wrote:
> On Sun, Aug 24, 2025 at 01:57:23PM +0200, Mathieu Dubois-Briand wrote:
>> +static int max7360_pwm_round_waveform_tohw(struct pwm_chip *chip,
>> +					   struct pwm_device *pwm,
>> +					   const struct pwm_waveform *wf,
>> +					   void *_wfhw)
>> +{
>> +	struct max7360_pwm_waveform *wfhw = _wfhw;
>> +	u64 duty_steps;
>> +
>> +	/*
>> +	 * Ignore user provided values for period_length_ns and duty_offset_ns:
>> +	 * we only support fixed period of MAX7360_PWM_PERIOD_NS and offset of 0.
>> +	 * Values from 0 to 254 as duty_steps will provide duty cycles of 0/256
>> +	 * to 254/256, while value 255 will provide a duty cycle of 100%.
>> +	 */
>> +	if (wf->duty_length_ns >= MAX7360_PWM_PERIOD_NS) {
>> +		duty_steps = MAX7360_PWM_MAX;
>> +	} else {
>> +		duty_steps = (u32)wf->duty_length_ns * MAX7360_PWM_STEPS / MAX7360_PWM_PERIOD_NS;
>> +		if (duty_steps == MAX7360_PWM_MAX)
>> +			duty_steps = MAX7360_PWM_MAX - 1;
>> +	}
>> +
>> +	wfhw->duty_steps = min(MAX7360_PWM_MAX, duty_steps);
>
> duty_steps is never bigger than MAX7360_PWM_MAX, isn't it? Then this can
> be simplified to just
>
> 	wfhw->duty_steps = duty_steps;
>

Ok, I reviewed this section and I do agree with you. I will prepare a
new patch to fix this line and will send it separately.

> Otherwise looks fine to me.
>
> To get this series forward, it's OK for me to apply the series as is via
> Lee's MFD tree and cope for this minor optimisation later. So:
>
> Acked-by: Uwe Kleine-König <ukleinek@...nel.org>
>
> Best regards
> Uwe

Thanks,
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com