diff mbox series

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

Message ID 588373a200d20da0fa6c2a6c7f1928b4818097e9.1610882271.git.baruch@tkos.co.il (mailing list archive)
State New, archived
Headers show
Series gpio: mvebu: pwm fixes and improvements | expand

Commit Message

Baruch Siach Jan. 17, 2021, 1:17 p.m. UTC 
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@armlinux.org.uk>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 drivers/gpio/gpio-mvebu.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

Comments

Bartosz Golaszewski Jan. 19, 2021, 11 a.m. UTC | #1 
On Sun, Jan 17, 2021 at 2:17 PM Baruch Siach <baruch@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@armlinux.org.uk>
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Baruch Siach <baruch@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
diff mbox series

Patch

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)