[PATCH v4 1/5] gpio: mvebu: fix pwm .get_state period calculation

[Bartosz Golaszewski]

On Sun, Jan 17, 2021 at 2:17 PM Baruch Siach <baruch at tkos.co.il> wrote:
>
> The period is the sum of on and off values. That is, calculate period as
>
>   ($on + $off) / clkrate
>
> instead of
>
>   $off / clkrate - $on / clkrate
>
> that makes no sense.
>
> Reported-by: Russell King <linux at armlinux.org.uk>
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> 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;
> -       }
>
>         regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u);
>         if (u)
> --
> 2.29.2
>

I applied this for fixes and will send out a PR to Linus T this week.
Once that's upstream I'll apply the rest for the next release.

Bartosz