[ Upstream commit 8caa81eb950cb2e9d2d6959b37d853162d197f57 ]
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@pengutron... 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 --- drivers/pwm/pwm-meson.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c index 3cf3bcf5ddfc..b2e6d00066d7 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 = {