pwm/tracing: Also record trace events for failed API calls

Record and report an error code for the events. This allows to report
about failed calls without ambiguity and so gives a more complete
picture.
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221130152148.2769768-3-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/core.c

@@ -115,8 +115,8 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	}
 
 	if (pwm->chip->ops->get_state) {
-		pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
-		trace_pwm_get(pwm, &pwm->state);
+		err = pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
+		trace_pwm_get(pwm, &pwm->state, err);
 
 		if (IS_ENABLED(CONFIG_PWM_DEBUG))
 			pwm->last = pwm->state;
@@ -458,8 +458,8 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 	 * checks.
 	 */
 
-	chip->ops->get_state(chip, pwm, &s1);
-	trace_pwm_get(pwm, &s1);
+	err = chip->ops->get_state(chip, pwm, &s1);
+	trace_pwm_get(pwm, &s1, err);
 
 	/*
 	 * The lowlevel driver either ignored .polarity (which is a bug) or as
@@ -515,16 +515,15 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 
 	/* reapply the state that the driver reported being configured. */
 	err = chip->ops->apply(chip, pwm, &s1);
+	trace_pwm_apply(pwm, &s1, err);
 	if (err) {
 		*last = s1;
 		dev_err(chip->dev, "failed to reapply current setting\n");
 		return;
 	}
 
-	trace_pwm_apply(pwm, &s1);
-
-	chip->ops->get_state(chip, pwm, last);
-	trace_pwm_get(pwm, last);
+	err = chip->ops->get_state(chip, pwm, last);
+	trace_pwm_get(pwm, last, err);
 
 	/* reapplication of the current state should give an exact match */
 	if (s1.enabled != last->enabled ||
@@ -572,11 +571,10 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
 		return 0;
 
 	err = chip->ops->apply(chip, pwm, state);
+	trace_pwm_apply(pwm, state, err);
 	if (err)
 		return err;
 
-	trace_pwm_apply(pwm, state);
-
 	pwm->state = *state;
 
 	/*

include/trace/events/pwm.h

@@ -10,9 +10,9 @@
 
 DECLARE_EVENT_CLASS(pwm,
 
-	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state),
+	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state, int err),
 
-	TP_ARGS(pwm, state),
+	TP_ARGS(pwm, state, err),
 
 	TP_STRUCT__entry(
 		__field(struct pwm_device *, pwm)
@@ -20,6 +20,7 @@ DECLARE_EVENT_CLASS(pwm,
 		__field(u64, duty_cycle)
 		__field(enum pwm_polarity, polarity)
 		__field(bool, enabled)
+		__field(int, err)
 	),
 
 	TP_fast_assign(
@@ -28,28 +29,27 @@ DECLARE_EVENT_CLASS(pwm,
 		__entry->duty_cycle = state->duty_cycle;
 		__entry->polarity = state->polarity;
 		__entry->enabled = state->enabled;
+		__entry->err = err;
 	),
 
-	TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d",
+	TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d",
 		  __entry->pwm, __entry->period, __entry->duty_cycle,
-		  __entry->polarity, __entry->enabled)
+		  __entry->polarity, __entry->enabled, __entry->err)
 
 );
 
 DEFINE_EVENT(pwm, pwm_apply,
 
-	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state),
-
-	TP_ARGS(pwm, state)
+	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state, int err),
 
+	TP_ARGS(pwm, state, err)
 );
 
 DEFINE_EVENT(pwm, pwm_get,
 
-	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state),
-
-	TP_ARGS(pwm, state)
+	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state, int err),
 
+	TP_ARGS(pwm, state, err)
 );
 
 #endif /* _TRACE_PWM_H */