Hi Geert, Thanks for your reply. Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> 於 2023年1月30日 週一 下午5:53寫道： > > 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? I think your inference is correct, I will use it. thanks a lot. > > > > > 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
