diff options
| author | Ondrej Jirman <megous@megous.com> | 2019-10-14 15:53:03 +0200 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2019-10-21 16:50:02 +0200 |
| commit | 50cc7e3e4f26e3bf5ed74a8d061195c4d2161b8b (patch) | |
| tree | 47ecb80f39a78819c4755025532984af5d673628 /drivers/pwm | |
| parent | 2d3aa06b5de097747d848a9d714987a4aa2303aa (diff) | |
| download | linux-50cc7e3e4f26e3bf5ed74a8d061195c4d2161b8b.tar.bz2 | |
pwm: sun4i: Fix incorrect calculation of duty_cycle/period
Since 5.4-rc1, pwm_apply_state calls ->get_state after ->apply
if available, and this revealed an issue with integer precision
when calculating duty_cycle and period for the currently set
state in ->get_state callback.
This issue manifested in broken backlight on several Allwinner
based devices.
Previously this worked, because ->apply updated the passed state
directly.
Fixes: deb9c462f4e53 ("pwm: sun4i: Don't update the state for the caller of pwm_apply_state")
Signed-off-by: Ondrej Jirman <megous@megous.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
| -rw-r--r-- | drivers/pwm/pwm-sun4i.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c index 53970d4ba695..581d23287333 100644 --- a/drivers/pwm/pwm-sun4i.c +++ b/drivers/pwm/pwm-sun4i.c @@ -137,10 +137,10 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip, val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm)); - tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); + tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); - tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val); + tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_PRD(val); state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); } |