[PATCH 1/5] gpio: mvebu: fix pwm get_state period calculation

[Uwe Kleine-König]

Hello Baruch,

$Subject ~= s/get_state/.get_state/ ?

On Mon, Jan 11, 2021 at 01:17:02PM +0200, Baruch Siach wrote:
> The period is the sum of on and off values.
> 
> Reported-by: Russell King <linux at armlinux.org.uk>
> Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
>  drivers/gpio/gpio-mvebu.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> index 672681a976f5..a912a8fed197 100644
> --- a/drivers/gpio/gpio-mvebu.c
> +++ b/drivers/gpio/gpio-mvebu.c
> @@ -676,20 +676,17 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
>  	else
>  		state->duty_cycle = 1;
>  
> +	val = (unsigned long long) u; /* on duration */
>  	regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
> -	val = (unsigned long long) u * NSEC_PER_SEC;
> +	val += (unsigned long long) u; /* period = on + off duration */
> +	val *= NSEC_PER_SEC;
>  	do_div(val, mvpwm->clk_rate);
> -	if (val < state->duty_cycle) {
> +	if (val > UINT_MAX)
> +		state->period = UINT_MAX;
> +	else if (val)
> +		state->period = val;
> +	else
>  		state->period = 1;
> -	} else {
> -		val -= state->duty_cycle;
> -		if (val > UINT_MAX)
> -			state->period = UINT_MAX;
> -		else if (val)
> -			state->period = val;
> -		else
> -			state->period = 1;
> -	}

The patch looks good, the patch description could be a bit more verbose.
Something like:

	Calculate the period as

		($on + $off) / clkrate

	instead of

		$off / clkrate - $on / clkrate

	.

Best regards
Uwe

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