[PATCH] pwm: stm32: Always do lazy disabling

[Uwe Kleine-König]

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 at baylibre.com>
---
 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 fba080daf445..fd754a99cf2e 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -452,8 +452,9 @@ 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;
 	}
 

base-commit: b8689bb9b901e5e2bc0f0905320b32e8c898a58b
-- 
2.43.0