diff options
author | Ondrej Jirman <megous@megous.com> | 2019-10-14 16:53:03 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-26 12:01:04 +0300 |
commit | e70290bb1f8fa625b0e9a98fd78efd3ec51fabcb (patch) | |
tree | 86c1bc0c7e3c59b52c6415e47c5091f400a51892 /drivers/pwm | |
parent | aff509a3a127f0f059f2da9ddcbf477a74585664 (diff) | |
download | linux-e70290bb1f8fa625b0e9a98fd78efd3ec51fabcb.tar.xz |
pwm: sun4i: Fix incorrect calculation of duty_cycle/period
[ Upstream commit 50cc7e3e4f26e3bf5ed74a8d061195c4d2161b8b ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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 6f5840a1a82d..05273725a9ff 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); } |