pwm: Disable PWM_DEBUG check for disabled states

When a PWM is requested to be disabled, the result is unspecified, the only
intention is to save some power. So skip all checks in this case.

All but two checks already only triggered for states with .enabled = true.
The first resulted in some false positive diagnostics, the other checked
for a condition that depending on hardware might not be implementable.

Similar if the lowlevel driver disabled the hardware this might be a valid
reaction and with .enabled = false all other state parameters are
unreliable, so skip further tests in this case, too.

All later usages of .enabled can be assumed to yield true, and so several
if conditions can be simplified.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/16d29212b09b66c286c1232b1ab0ec0f8d510aae.1751994988.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

1 files changed, 20 insertions, 12 deletions

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index bff0057d87a4..d5d2dfbe4ade 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -497,6 +497,13 @@ static void pwm_apply_debug(struct pwm_device *pwm,
 		return;
 
 	/*
+	 * If a disabled PWM was requested the result is unspecified, so nothing
+	 * to check.
+	 */
+	if (!state->enabled)
+		return;
+
+	/*
 	 * *state was just applied. Read out the hardware state and do some
 	 * checks.
 	 */
@@ -508,15 +515,22 @@ static void pwm_apply_debug(struct pwm_device *pwm,
 		return;
 
 	/*
+	 * If the PWM was disabled that's maybe strange but there is nothing
+	 * that can be sensibly checked then. So return early.
+	 */
+	if (!s1.enabled)
+		return;
+
+	/*
 	 * The lowlevel driver either ignored .polarity (which is a bug) or as
 	 * best effort inverted .polarity and fixed .duty_cycle respectively.
 	 * Undo this inversion and fixup for further tests.
 	 */
-	if (s1.enabled && s1.polarity != state->polarity) {
+	if (s1.polarity != state->polarity) {
 		s2.polarity = state->polarity;
 		s2.duty_cycle = s1.period - s1.duty_cycle;
 		s2.period = s1.period;
-		s2.enabled = s1.enabled;
+		s2.enabled = true;
 	} else {
 		s2 = s1;
 	}
@@ -525,8 +539,7 @@ static void pwm_apply_debug(struct pwm_device *pwm,
 	    state->duty_cycle < state->period)
 		dev_warn(pwmchip_parent(chip), ".apply ignored .polarity\n");
 
-	if (state->enabled && s2.enabled &&
-	    last->polarity == state->polarity &&
+	if (last->polarity == state->polarity &&
 	    last->period > s2.period &&
 	    last->period <= state->period)
 		dev_warn(pwmchip_parent(chip),
@@ -537,13 +550,12 @@ static void pwm_apply_debug(struct pwm_device *pwm,
 	 * Rounding period up is fine only if duty_cycle is 0 then, because a
 	 * flat line doesn't have a characteristic period.
 	 */
-	if (state->enabled && s2.enabled && state->period < s2.period && s2.duty_cycle)
+	if (state->period < s2.period && s2.duty_cycle)
 		dev_warn(pwmchip_parent(chip),
 			 ".apply is supposed to round down period (requested: %llu, applied: %llu)\n",
 			 state->period, s2.period);
 
-	if (state->enabled &&
-	    last->polarity == state->polarity &&
+	if (last->polarity == state->polarity &&
 	    last->period == s2.period &&
 	    last->duty_cycle > s2.duty_cycle &&
 	    last->duty_cycle <= state->duty_cycle)
@@ -553,16 +565,12 @@ static void pwm_apply_debug(struct pwm_device *pwm,
 			 s2.duty_cycle, s2.period,
 			 last->duty_cycle, last->period);
 
-	if (state->enabled && s2.enabled && state->duty_cycle < s2.duty_cycle)
+	if (state->duty_cycle < s2.duty_cycle)
 		dev_warn(pwmchip_parent(chip),
 			 ".apply is supposed to round down duty_cycle (requested: %llu/%llu, applied: %llu/%llu)\n",
 			 state->duty_cycle, state->period,
 			 s2.duty_cycle, s2.period);
 
-	if (!state->enabled && s2.enabled && s2.duty_cycle > 0)
-		dev_warn(pwmchip_parent(chip),
-			 "requested disabled, but yielded enabled with duty > 0\n");
-
 	/* reapply the state that the driver reported being configured. */
 	err = chip->ops->apply(chip, pwm, &s1);
 	trace_pwm_apply(pwm, &s1, err);