4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx>
[ Upstream commit 7346e7a058a2c9aa9ff1cc699c7bf18a402d9f84 ]
When the state changes from enabled to disabled, polarity, duty_cycle
and period are not configured in hardware and TIM_CCER_CCxE is just
cleared. However if the state changes from one disabled state to
another, all parameters are written to hardware because the early exit
from stm32_pwm_apply() is only taken if the pwm is currently enabled.
This yields surprises like: Applying
{ .period = 1, .duty_cycle = 0, .enabled = false }
succeeds if the pwm is initially on, but fails if it's already off
because 1 is a too small period.
Update the check for lazy disable to always exit early if the target
state is disabled, no matter what is currently configured.
Fixes: 7edf7369205b ("pwm: Add driver for STM32 plaftorm")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240703110010.672654-2-u.kleine-koenig@xxxxxxxxxxxx
Signed-off-by: Uwe Kleine-König <ukleinek@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/pwm/pwm-stm32.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index ee7197b8e4ef7..5325e804ca24f 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -451,8 +451,9 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
enabled = pwm->state.enabled;
- if (enabled && !state->enabled) {
- stm32_pwm_disable(priv, pwm->hwpwm);
+ if (!state->enabled) {
+ if (enabled)
+ stm32_pwm_disable(priv, pwm->hwpwm);
return 0;
}
--
2.43.0
