diff options
| author | Paul Cercueil <paul@crapouillou.net> | 2020-05-27 14:52:23 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-24 18:50:52 +0300 |
| commit | a6030d71e62d3e0e270bf3b7fb48d32a636732db (patch) | |
| tree | cdcecabd48952a64020587ea252b4eb1f81194f3 /drivers/pwm | |
| parent | d0da4be602882214109dd4444d777c8277e1e048 (diff) | |
| download | linux-a6030d71e62d3e0e270bf3b7fb48d32a636732db.tar.xz | |
pwm: jz4740: Enhance precision in calculation of duty cycle
commit 9017dc4fbd59c09463019ce494cfe36d654495a8 upstream.
Calculating the hardware value for the duty from the hardware value of
the period resulted in a precision loss versus calculating it from the
clock rate directly.
(Also remove a cast that doesn't really need to be here)
Fixes: f6b8a5700057 ("pwm: Add Ingenic JZ4740 support")
Cc: <stable@vger.kernel.org>
Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
[ukl: backport to v5.4.y and adapt commit log accordingly]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/pwm')
| -rw-r--r-- | drivers/pwm/pwm-jz4740.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c index 9d78cc21cb12..d0f5c69930d0 100644 --- a/drivers/pwm/pwm-jz4740.c +++ b/drivers/pwm/pwm-jz4740.c @@ -108,8 +108,8 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, if (prescaler == 6) return -EINVAL; - tmp = (unsigned long long)period * state->duty_cycle; - do_div(tmp, state->period); + tmp = (unsigned long long)rate * state->duty_cycle; + do_div(tmp, NSEC_PER_SEC); duty = period - tmp; if (duty >= period) |