linux-kernel - [PATCH v2] pwm: stm32: Always program polarity

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Message-Id: <20260108-stm32-pwm-v2-1-ced582974f8b@geanix.com>
Date: Thu, 08 Jan 2026 13:45:23 +0100
From: Sean Nyekjaer <sean@...nix.com>
To: Fabrice Gasnier <fabrice.gasnier@...s.st.com>, 
 Uwe Kleine-König <ukleinek@...nel.org>, 
 Maxime Coquelin <mcoquelin.stm32@...il.com>, 
 Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: Uwe Kleine-König <u.kleine-koenig@...libre.com>, 
 linux-pwm@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 stable@...r.kernel.org, Sean Nyekjaer <sean@...nix.com>
Subject: [PATCH v2] pwm: stm32: Always program polarity

Commit 7346e7a058a2 ("pwm: stm32: Always do lazy disabling") triggered a
regression where PWM polarity changes could be ignored.

stm32_pwm_set_polarity() was skipped due to a mismatch between the
cached pwm->state.polarity and the actual hardware state, leaving the
hardware polarity unchanged.

Fixes: 7edf7369205b ("pwm: Add driver for STM32 plaftorm")
Cc: stable@...r.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@...nix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@...nel.org>
---
This patch is only applicable for stable tree's <= 6.12
---
Changes in v2:
- Taken patch improvements for Uwe
- Link to v1: https://lore.kernel.org/r/20260106-stm32-pwm-v1-1-33e9e8a9fc33@geanix.com
---
 drivers/pwm/pwm-stm32.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index eb24054f9729734da21eb96f2e37af03339e3440..86e6eb7396f67990249509dd347cb5a60c9ccf16 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -458,8 +458,7 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		return 0;
 	}
 
-	if (state->polarity != pwm->state.polarity)
-		stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
+	stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
 
 	ret = stm32_pwm_config(priv, pwm->hwpwm,
 			       state->duty_cycle, state->period);

---
base-commit: eb18504ca5cf1e6a76a752b73daf0ef51de3551b
change-id: 20260105-stm32-pwm-91cb843680f4

Best regards,
-- 
Sean Nyekjaer <sean@...nix.com>