From: Uwe Kleine-König u.kleine-koenig@pengutronix.de
[ Upstream commit 937efa29e70f7f8424b74631375dcb35d82a4614 ]
With the original code a request for period = 65536000 ns and period = 32768000 ns yields the same register settings (which results in 32768000 ns) because the value for pwmc0 was miscalculated.
Also simplify using that fls(0) is 0.
Fixes: 721b595744f1 ("pwm: visconti: Add Toshiba Visconti SoC PWM support") Signed-off-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Acked-by: Nobuhiro Iwamatsu nobuhiro1.iwamatsu@toshiba.co.jp Signed-off-by: Thierry Reding thierry.reding@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pwm/pwm-visconti.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/pwm/pwm-visconti.c b/drivers/pwm/pwm-visconti.c index 46d903786366..af4e37d3e3a6 100644 --- a/drivers/pwm/pwm-visconti.c +++ b/drivers/pwm/pwm-visconti.c @@ -82,17 +82,14 @@ static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, return -ERANGE;
/* - * PWMC controls a divider that divides the input clk by a - * power of two between 1 and 8. As a smaller divider yields - * higher precision, pick the smallest possible one. + * PWMC controls a divider that divides the input clk by a power of two + * between 1 and 8. As a smaller divider yields higher precision, pick + * the smallest possible one. As period is at most 0xffff << 3, pwmc0 is + * in the intended range [0..3]. */ - if (period > 0xffff) { - pwmc0 = ilog2(period >> 16); - if (WARN_ON(pwmc0 > 3)) - return -EINVAL; - } else { - pwmc0 = 0; - } + pwmc0 = fls(period >> 16); + if (WARN_ON(pwmc0 > 3)) + return -EINVAL;
period >>= pwmc0; duty_cycle >>= pwmc0;