diff options
| author | Baruch Siach <baruch@tkos.co.il> | 2021-01-20 19:16:25 +0300 |
|---|---|---|
| committer | Bartosz Golaszewski <bgolaszewski@baylibre.com> | 2021-02-15 13:43:30 +0300 |
| commit | aa37e27f610fe3e7539c066d9c1f5304390086d6 (patch) | |
| tree | 40e5f553d7fb46c1976af9952b053db5044d6f7f /drivers/gpio | |
| parent | 4bf2426103d2dd89c1b48bd5eba8cd16903ec40b (diff) | |
| download | linux-aa37e27f610fe3e7539c066d9c1f5304390086d6.tar.xz | |
gpio: mvebu: improve pwm period calculation accuracy
Change 'off' register value calculation from
$off = (period - duty_cycle) * clkrate / NSEC_PER_SEC
to
$off = (period * clkrate / NSEC_PER_SEC) - $on
That is, divide the full period value to reduce rounding error.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/gpio-mvebu.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index a912a8fed197..c424d88e9e2b 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, else on = 1; - val = (unsigned long long) mvpwm->clk_rate * - (state->period - state->duty_cycle); + val = (unsigned long long) mvpwm->clk_rate * state->period; do_div(val, NSEC_PER_SEC); + val -= on; if (val > UINT_MAX) return -EINVAL; if (val) |