pwm: Handle .get_state() failures

This suppresses diagnosis for PWM_DEBUG routines and makes sure that
pwm->state isn't modified in pwm_device_request() if .get_state() fails.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221130152148.2769768-12-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>

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 61d15510fdd77b0c5761cdb3b8bca42a95c060d4..e01147f66e15aa752c8a1331372ffa0440c07d4c 100644 (file)
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -115,8 +115,13 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
        }
 
        if (pwm->chip->ops->get_state) {
-               err = pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
-               trace_pwm_get(pwm, &pwm->state, err);
+               struct pwm_state state;
+
+               err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
+               trace_pwm_get(pwm, &state, err);
+
+               if (!err)
+                       pwm->state = state;
 
                if (IS_ENABLED(CONFIG_PWM_DEBUG))
                        pwm->last = pwm->state;
@@ -460,6 +465,9 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 
        err = chip->ops->get_state(chip, pwm, &s1);
        trace_pwm_get(pwm, &s1, err);
+       if (err)
+               /* If that failed there isn't much to debug */
+               return;
 
        /*
         * The lowlevel driver either ignored .polarity (which is a bug) or as
@@ -524,6 +532,8 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 
        err = chip->ops->get_state(chip, pwm, last);
        trace_pwm_get(pwm, last, err);
+       if (err)
+               return;
 
        /* reapplication of the current state should give an exact match */
        if (s1.enabled != last->enabled ||