Re: [PATCH v4 06/16] pwm: lpss: Correct get_state result for base_unit == 0

Andy Shevchenko
2020-07-09T14:50:18Z

On Wed, Jul 08, 2020 at 11:14:22PM +0200, Hans de Goede wrote:
> The datasheet specifies that programming the base_unit part of the
> ctrl register to 0 results in a contineous low signal.
>
> Adjust the get_state method to reflect this by setting pwm_state.period
> to 1 and duty_cycle to 0.

...

> + if (freq == 0) {
> + /* In this case the PWM outputs a continous low signal */

> + state->period = 1;

I guess this should be something like half of the range (so base unit calc
will give 128). Because with period = 1 (too small) it will give too small
base unit (if apply) and as a result we get high frequency pulses.

> + state->duty_cycle = 0;
> + } else {
> state->period = NSEC_PER_SEC / (unsigned long)freq;
> + on_time_div *= state->period;
> + do_div(on_time_div, 255);
> + state->duty_cycle = on_time_div;
> + }

--
With Best Regards,
Andy Shevchenko