linux-kernel - Re: [PATCH v8 2/5] pwm: Add Apple PWM controller

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Date:   Fri, 10 Mar 2023 22:46:58 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     fnkl.kernel@...il.com
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        - <asahi@...ts.linux.dev>, Hector Martin <marcan@...can.st>,
        Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v8 2/5] pwm: Add Apple PWM controller

Hello Sascha,

On Fri, Mar 10, 2023 at 07:44:08PM +0100, Sasha Finkelstein via B4 Relay wrote:
> +static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			   const struct pwm_state *state)
> +{
> +	struct apple_pwm *fpwm;
> +
> +	if (state->polarity == PWM_POLARITY_INVERSED)
> +		return -EINVAL;
> +
> +	fpwm = to_apple_pwm(chip);
> +	if (state->enabled) {
> +		u64 on_cycles, off_cycles;
> +
> +		on_cycles = mul_u64_u64_div_u64(fpwm->clkrate,
> +						state->duty_cycle, NSEC_PER_SEC);
> +		if (on_cycles > 0xFFFFFFFF)
> +			on_cycles = 0xFFFFFFFF;
> +
> +		off_cycles = mul_u64_u64_div_u64(fpwm->clkrate,
> +						 state->period, NSEC_PER_SEC) - on_cycles;
> +		if (off_cycles > 0xFFFFFFFF)
> +			return -ERANGE;

This is still wrong and needs clamping, too.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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