[PATCH v2] pwm: stm32: Always program polarity

[PATCH v2] pwm: stm32: Always program polarity

[Sean Nyekjaer]

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@vger.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@kernel.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@geanix.com>

Re: [PATCH v2] pwm: stm32: Always program polarity

[Uwe Kleine-König]

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Hello Greg,

On Thu, Jan 08, 2026 at 01:45:23PM +0100, Sean Nyekjaer wrote:
> 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@vger.kernel.org # <= 6.12
> Signed-off-by: Sean Nyekjaer <sean@geanix.com>
> Co-developed-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

> ---
> This patch is only applicable for stable tree's <= 6.12

Can you please apply this patch to v6.12.x and older? The problem fixed
here doesn't happen in mainline since commit deaba9cff809 ("pwm: stm32:
Implementation of the waveform callbacks"). That mainline commit however
is too intrusive to backport it to stable, not even considering its
dependencies (e.g. 17e40c25158f ("pwm: New abstraction for PWM
waveforms")). 

I assume such an exception to the sable process is ok and the patch is
simple enough to be easily reviewable? If not, tell me, then I can apply
the patch and merge it (with `-s ours`) into my next PWM pull request to
Linus :-)

Best regards
Uwe

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Patch "pwm: stm32: Always program polarity" has been added to the 5.10-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    pwm: stm32: Always program polarity

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pwm-stm32-always-program-polarity.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From sean@geanix.com  Fri Jan  9 11:22:32 2026
From: Sean Nyekjaer <sean@geanix.com>
Date: Thu, 08 Jan 2026 13:45:23 +0100
Subject: pwm: stm32: Always program polarity
To: "Fabrice Gasnier" <fabrice.gasnier@foss.st.com>, "Uwe Kleine-König" <ukleinek@kernel.org>, "Maxime Coquelin" <mcoquelin.stm32@gmail.com>, "Alexandre Torgue" <alexandre.torgue@foss.st.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@baylibre.com>, linux-pwm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Sean Nyekjaer" <sean@geanix.com>
Message-ID: <20260108-stm32-pwm-v2-1-ced582974f8b@geanix.com>

From: Sean Nyekjaer <sean@geanix.com>

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@vger.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
---
 drivers/pwm/pwm-stm32.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -458,8 +458,7 @@ static int stm32_pwm_apply(struct pwm_ch
 		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);


Patches currently in stable-queue which might be from sean@geanix.com are

queue-5.10/pwm-stm32-always-program-polarity.patch

Patch "pwm: stm32: Always program polarity" has been added to the 5.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    pwm: stm32: Always program polarity

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pwm-stm32-always-program-polarity.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From sean@geanix.com  Fri Jan  9 11:22:32 2026
From: Sean Nyekjaer <sean@geanix.com>
Date: Thu, 08 Jan 2026 13:45:23 +0100
Subject: pwm: stm32: Always program polarity
To: "Fabrice Gasnier" <fabrice.gasnier@foss.st.com>, "Uwe Kleine-König" <ukleinek@kernel.org>, "Maxime Coquelin" <mcoquelin.stm32@gmail.com>, "Alexandre Torgue" <alexandre.torgue@foss.st.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@baylibre.com>, linux-pwm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Sean Nyekjaer" <sean@geanix.com>
Message-ID: <20260108-stm32-pwm-v2-1-ced582974f8b@geanix.com>

From: Sean Nyekjaer <sean@geanix.com>

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@vger.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
---
 drivers/pwm/pwm-stm32.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -458,8 +458,7 @@ static int stm32_pwm_apply(struct pwm_ch
 		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);


Patches currently in stable-queue which might be from sean@geanix.com are

queue-5.15/pwm-stm32-always-program-polarity.patch

Patch "pwm: stm32: Always program polarity" has been added to the 6.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    pwm: stm32: Always program polarity

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pwm-stm32-always-program-polarity.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From sean@geanix.com  Fri Jan  9 11:22:32 2026
From: Sean Nyekjaer <sean@geanix.com>
Date: Thu, 08 Jan 2026 13:45:23 +0100
Subject: pwm: stm32: Always program polarity
To: "Fabrice Gasnier" <fabrice.gasnier@foss.st.com>, "Uwe Kleine-König" <ukleinek@kernel.org>, "Maxime Coquelin" <mcoquelin.stm32@gmail.com>, "Alexandre Torgue" <alexandre.torgue@foss.st.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@baylibre.com>, linux-pwm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Sean Nyekjaer" <sean@geanix.com>
Message-ID: <20260108-stm32-pwm-v2-1-ced582974f8b@geanix.com>

From: Sean Nyekjaer <sean@geanix.com>

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@vger.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
---
 drivers/pwm/pwm-stm32.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -458,8 +458,7 @@ static int stm32_pwm_apply(struct pwm_ch
 		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);


Patches currently in stable-queue which might be from sean@geanix.com are

queue-6.1/pwm-stm32-always-program-polarity.patch

Patch "pwm: stm32: Always program polarity" has been added to the 6.6-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    pwm: stm32: Always program polarity

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pwm-stm32-always-program-polarity.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From sean@geanix.com  Fri Jan  9 11:22:32 2026
From: Sean Nyekjaer <sean@geanix.com>
Date: Thu, 08 Jan 2026 13:45:23 +0100
Subject: pwm: stm32: Always program polarity
To: "Fabrice Gasnier" <fabrice.gasnier@foss.st.com>, "Uwe Kleine-König" <ukleinek@kernel.org>, "Maxime Coquelin" <mcoquelin.stm32@gmail.com>, "Alexandre Torgue" <alexandre.torgue@foss.st.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@baylibre.com>, linux-pwm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Sean Nyekjaer" <sean@geanix.com>
Message-ID: <20260108-stm32-pwm-v2-1-ced582974f8b@geanix.com>

From: Sean Nyekjaer <sean@geanix.com>

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@vger.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
---
 drivers/pwm/pwm-stm32.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -462,8 +462,7 @@ static int stm32_pwm_apply(struct pwm_ch
 		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);


Patches currently in stable-queue which might be from sean@geanix.com are

queue-6.6/pwm-stm32-always-program-polarity.patch

Patch "pwm: stm32: Always program polarity" has been added to the 6.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    pwm: stm32: Always program polarity

to the 6.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pwm-stm32-always-program-polarity.patch
and it can be found in the queue-6.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From sean@geanix.com  Fri Jan  9 11:22:32 2026
From: Sean Nyekjaer <sean@geanix.com>
Date: Thu, 08 Jan 2026 13:45:23 +0100
Subject: pwm: stm32: Always program polarity
To: "Fabrice Gasnier" <fabrice.gasnier@foss.st.com>, "Uwe Kleine-König" <ukleinek@kernel.org>, "Maxime Coquelin" <mcoquelin.stm32@gmail.com>, "Alexandre Torgue" <alexandre.torgue@foss.st.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@baylibre.com>, linux-pwm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Sean Nyekjaer" <sean@geanix.com>
Message-ID: <20260108-stm32-pwm-v2-1-ced582974f8b@geanix.com>

From: Sean Nyekjaer <sean@geanix.com>

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@vger.kernel.org # <= 6.12
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Co-developed-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
---
 drivers/pwm/pwm-stm32.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -458,8 +458,7 @@ static int stm32_pwm_apply(struct pwm_ch
 		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);


Patches currently in stable-queue which might be from sean@geanix.com are

queue-6.12/pwm-stm32-always-program-polarity.patch