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SubjectRe: [PATCH 1/2] pwm: meson: consider 128 a valid pre-divider
Hello Martin,

On Mon, Apr 01, 2019 at 08:18:16PM +0200, Martin Blumenstingl wrote:
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index f6e738ad7bd9..4b708c1fcb1d 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -188,7 +188,7 @@ static int meson_pwm_calc(struct meson_pwm *meson,
> do_div(fin_ps, fin_freq);
>
> /* Calc pre_div with the period */
> - for (pre_div = 0; pre_div < MISC_CLK_DIV_MASK; pre_div++) {
> + for (pre_div = 0; pre_div <= MISC_CLK_DIV_MASK; pre_div++) {
> cnt = DIV_ROUND_CLOSEST_ULL((u64)period * 1000,
> fin_ps * (pre_div + 1));
> dev_dbg(meson->chip.dev, "fin_ps=%llu pre_div=%u cnt=%u\n",

You could even calculate pre_div without the loop.

Something like:

u64 pre_div = (u64)period * rate;
do_div_round_up(pre_div, NSEC_PER_SEC * 0xffff);
pre_div--;

(I didn't check rounding and maybe its off by one and ...) This would
also get rid of the strange 1000 that is currently used in the
calculation without a real benefit (unless I missed something).

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |

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