5.4-stable review patch. If anyone has any objections, please let me know.
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From: Uwe Kleine-König u.kleine-koenig@baylibre.com
[ 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@baylibre.com Link: https://lore.kernel.org/r/20240703110010.672654-2-u.kleine-koenig@baylibre.c... Signed-off-by: Uwe Kleine-König ukleinek@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 4b20ff6f687b8..9e94a797dcf31 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; }