diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2023-03-22 22:45:44 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-04-26 11:24:06 +0200 |
| commit | 760c2e6dee325e7f8b2303c1c06379dccd6682f2 (patch) | |
| tree | 161ef651e693140c76c77156dbeedcdaf812c8ff | |
| parent | 7f2b8046da837db765c092cfdecb5c16cf840f11 (diff) | |
pwm: meson: Explicitly set .polarity in .get_state()
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@amazon.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20230310191405.2606296-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/pwm/pwm-meson.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c index 6245bbdb6e6c..3c81858a8261 100644 --- a/drivers/pwm/pwm-meson.c +++ b/drivers/pwm/pwm-meson.c @@ -168,6 +168,12 @@ static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm, 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; @@ -366,6 +372,7 @@ static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, state->period = 0; state->duty_cycle = 0; } + state->polarity = PWM_POLARITY_NORMAL; } static const struct pwm_ops meson_pwm_ops = { |