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pwm: Restore initial state if a legacy callback fails 

It is not entirely accurate to go back to the initial state after e.g.
.enable() failed, as .config() still modified the hardware, but this same
inconsistency exists for drivers that implement .apply().

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Uwe Kleine-König 2021-07-01 09:29:27 +02:00 committed by Thierry Reding
parent 92f69e582e
commit e45a178e9e
1 changed files with 8 additions and 6 deletions
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14
drivers/pwm/core.c
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@ -526,10 +526,8 @@ static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
struct pwm_state initial_state = pwm->state;
/*
* FIXME: restore the initial state in case of error.
*/
if (state->polarity != pwm->state.polarity) {
if (!chip->ops->set_polarity)
return -EINVAL;
@ -550,7 +548,7 @@ static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
err = chip->ops->set_polarity(chip, pwm, state->polarity);
if (err)
return err;
goto rollback;
pwm->state.polarity = state->polarity;
}
@ -573,7 +571,7 @@ static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
state->duty_cycle,
state->period);
if (err)
return err;
goto rollback;
pwm->state.period = state->period;
pwm->state.duty_cycle = state->duty_cycle;
@ -581,10 +579,14 @@ static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
if (!pwm->state.enabled) {
err = chip->ops->enable(chip, pwm);
if (err)
return err;
goto rollback;
}
return 0;
rollback:
pwm->state = initial_state;
return err;
}
/**