Patch "pwm: meson: Explicitly set .polarity in .get_state()" has been added to the 5.15-stable tree

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

    pwm: meson: Explicitly set .polarity in .get_state()

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-meson-explicitly-set-.polarity-in-.get_state.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@xxxxxxxxxxxxxxx> know about it.


>From 8caa81eb950cb2e9d2d6959b37d853162d197f57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@xxxxxxxxxxxxxx>
Date: Wed, 22 Mar 2023 22:45:44 +0100
Subject: pwm: meson: Explicitly set .polarity in .get_state()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>

commit 8caa81eb950cb2e9d2d6959b37d853162d197f57 upstream.

The driver only supports normal polarity. Complete the implementation of
.get_state() by setting .polarity accordingly.

This fixes a regression that was possible since commit c73a3107624d
("pwm: Handle .get_state() failures") which stopped to zero-initialize
the state passed to the .get_state() callback. This was reported at
https://forum.odroid.com/viewtopic.php?f=177&t=46360 . While this was an
unintended side effect, the real issue is the driver's callback not
setting the polarity.

There is a complicating fact, that the .apply() callback fakes support
for inversed polarity. This is not (and cannot) be matched by
.get_state(). As fixing this isn't easy, only point it out in a comment
to prevent authors of other drivers from copying that approach.

Fixes: c375bcbaabdb ("pwm: meson: Read the full hardware state in meson_pwm_get_state()")
Reported-by: Munehisa Kamata <kamatam@xxxxxxxxxx>
Acked-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230310191405.2606296-1-u.kleine-koenig@xxxxxxxxxxxxxx
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/pwm/pwm-meson.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -168,6 +168,12 @@ static int meson_pwm_calc(struct meson_p
 	duty = state->duty_cycle;
 	period = state->period;
 
+	/*
+	 * Note this is wrong. The result is an output wave that isn't really
+	 * inverted and so is wrongly identified by .get_state as normal.
+	 * Fixing this needs some care however as some machines might rely on
+	 * this.
+	 */
 	if (state->polarity == PWM_POLARITY_INVERSED)
 		duty = period - duty;
 
@@ -304,6 +310,8 @@ static int meson_pwm_apply(struct pwm_ch
 		meson_pwm_enable(meson, pwm);
 	}
 
+	state->polarity = PWM_POLARITY_NORMAL;
+
 	return 0;
 }
 


Patches currently in stable-queue which might be from u.kleine-koenig@xxxxxxxxxxxxxx are

queue-5.15/pwm-meson-explicitly-set-.polarity-in-.get_state.patch



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