Hi Nylon, On Mon, Jan 30, 2023 at 10:32 AM Nylon Chen <nylon.chen@xxxxxxxxxx> wrote: > The `frac` variable represents the pulse inactive time, and the result of > this algorithm is the pulse active time. Therefore, we must reverse the > result. > > The reference is SiFive FU740-C000 Manual[0]. > > [0]: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf > > Signed-off-by: Nylon Chen <nylon.chen@xxxxxxxxxx> Thanks for your patch! > --- a/drivers/pwm/pwm-sifive.c > +++ b/drivers/pwm/pwm-sifive.c > @@ -158,6 +158,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, > frac = DIV64_U64_ROUND_CLOSEST(num, state->period); > /* The hardware cannot generate a 100% duty cycle */ > frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1); > + frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac; Shouldn't the inversion be done before the hardware limitation fixup? > > mutex_lock(&ddata->lock); > if (state->period != ddata->approx_period) { Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
