On Tue, Jan 26, 2021 at 11:00:11AM +0200, Baruch Siach wrote:
> commit e73b0101ae5124bf7cd3fb5d250302ad2f16a416 upstream.
>
> 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@xxxxxxxxxxxxxxx>
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
Doesn't this need something like:
[baruch: Backported to 5.10]
plus a new S-o-B?
> ---
>
> This backported patch applies to all kernels between 4.14 and 5.10
> (inclusive).
> ---
> drivers/gpio/gpio-mvebu.c | 25 ++++++++++---------------
> 1 file changed, 10 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> index 2f245594a90a..ed7c5fc47f52 100644
> --- a/drivers/gpio/gpio-mvebu.c
> +++ b/drivers/gpio/gpio-mvebu.c
> @@ -660,9 +660,8 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
>
> spin_lock_irqsave(&mvpwm->lock, flags);
>
> - val = (unsigned long long)
> - readl_relaxed(mvebu_pwmreg_blink_on_duration(mvpwm));
> - val *= NSEC_PER_SEC;
> + u = readl_relaxed(mvebu_pwmreg_blink_on_duration(mvpwm));
> + val = (unsigned long long) u * NSEC_PER_SEC;
> do_div(val, mvpwm->clk_rate);
> if (val > UINT_MAX)
> state->duty_cycle = UINT_MAX;
> @@ -671,21 +670,17 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
> else
> state->duty_cycle = 1;
>
> - val = (unsigned long long)
> - readl_relaxed(mvebu_pwmreg_blink_off_duration(mvpwm));
> + val = (unsigned long long) u; /* on duration */
> + /* period = on + off duration */
> + val += readl_relaxed(mvebu_pwmreg_blink_off_duration(mvpwm));
> 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)
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Thanks
Uwe
--
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