Re: [PATCH 3/5] gpio: mvebu: make pwm apply/get_state closer to idempotent - Uwe Kleine-König

From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Baruch Siach <baruch@tkos.co.il>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Gregory Clement <gregory.clement@bootlin.com>,
	Russell King <linux@armlinux.org.uk>,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Chris Packham <chris.packham@alliedtelesis.co.nz>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Ralph Sennhauser <ralph.sennhauser@gmail.com>,
	linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/5] gpio: mvebu: make pwm apply/get_state closer to idempotent
Date: Mon, 11 Jan 2021 21:20:21 +0100	[thread overview]
Message-ID: <20210111202021.bspxeo73co7vxk6x@pengutronix.de> (raw)
In-Reply-To: <1c8864722e4c74d1d8d5d4a213998a1672be9992.1610362661.git.baruch@tkos.co.il>

[-- Attachment #1: Type: text/plain, Size: 2277 bytes --]

On Mon, Jan 11, 2021 at 01:17:04PM +0200, Baruch Siach wrote:
> Round up the result of division in period/duty_cycle calculation to make
> the result closer to idempotent.
> 
> Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
>  drivers/gpio/gpio-mvebu.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> index c424d88e9e2b..6fc64846eda3 100644
> --- a/drivers/gpio/gpio-mvebu.c
> +++ b/drivers/gpio/gpio-mvebu.c
> @@ -668,7 +668,7 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
>  
>  	regmap_read(mvpwm->regs, mvebu_pwmreg_blink_on_duration(mvpwm), &u);
>  	val = (unsigned long long) u * NSEC_PER_SEC;
> -	do_div(val, mvpwm->clk_rate);
> +	val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
>  	if (val > UINT_MAX)
>  		state->duty_cycle = UINT_MAX;
>  	else if (val)
> @@ -680,7 +680,7 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
>  	regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
>  	val += (unsigned long long) u; /* period = on + off duration */
>  	val *= NSEC_PER_SEC;
> -	do_div(val, mvpwm->clk_rate);
> +	val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
>  	if (val > UINT_MAX)
>  		state->period = UINT_MAX;
>  	else if (val)
> @@ -707,7 +707,7 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  	unsigned int on, off;
>  
>  	val = (unsigned long long) mvpwm->clk_rate * state->duty_cycle;
> -	do_div(val, NSEC_PER_SEC);
> +	val = DIV_ROUND_UP_ULL(val, NSEC_PER_SEC);

.apply must continue to round down.

Best regards
Uwe

>  	if (val > UINT_MAX)
>  		return -EINVAL;
>  	if (val)
> @@ -716,7 +716,7 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  		on = 1;
>  
>  	val = (unsigned long long) mvpwm->clk_rate * state->period;
> -	do_div(val, NSEC_PER_SEC);
> +	val = DIV_ROUND_UP_ULL(val, NSEC_PER_SEC);
>  	val -= on;
>  	if (val > UINT_MAX)
>  		return -EINVAL;
> -- 
> 2.29.2
> 
> 

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]