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authorOndrej Jirman <megous@megous.com>2019-10-14 15:53:03 +0200
committerThierry Reding <thierry.reding@gmail.com>2019-10-21 16:50:02 +0200
commit50cc7e3e4f26e3bf5ed74a8d061195c4d2161b8b (patch)
tree47ecb80f39a78819c4755025532984af5d673628 /drivers/pwm
parent2d3aa06b5de097747d848a9d714987a4aa2303aa (diff)
downloadlinux-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.c4
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);
}