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>
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;
state->duty_cycle = 0;
}
+ state->polarity = PWM_POLARITY_NORMAL;
+
return 0;
}