diff options
| -rw-r--r-- | drivers/pwm/core.c | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index cf6d91f1a9e6..8acbcf5b6673 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -137,6 +137,25 @@ static void pwm_apply_debug(struct pwm_device *pwm, } } +static bool pwm_state_valid(const struct pwm_state *state) +{ + /* + * For a disabled state all other state description is irrelevant and + * and supposed to be ignored. So also ignore any strange values and + * consider the state ok. + */ + if (state->enabled) + return true; + + if (!state->period) + return false; + + if (state->duty_cycle > state->period) + return false; + + return true; +} + /** * __pwm_apply() - atomically apply a new state to a PWM device * @pwm: PWM device @@ -147,10 +166,26 @@ static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state) struct pwm_chip *chip; int err; - if (!pwm || !state || !state->period || - state->duty_cycle > state->period) + if (!pwm || !state) return -EINVAL; + if (!pwm_state_valid(state)) { + /* + * Allow to transition from one invalid state to another. + * This ensures that you can e.g. change the polarity while + * the period is zero. (This happens on stm32 when the hardware + * is in its poweron default state.) This greatly simplifies + * working with the sysfs API where you can only change one + * parameter at a time. + */ + if (!pwm_state_valid(&pwm->state)) { + pwm->state = *state; + return 0; + } + + return -EINVAL; + } + chip = pwm->chip; if (state->period == pwm->state.period && |