Hello Fabrice, On Mon, Feb 11, 2019 at 05:12:02PM +0100, Fabrice Gasnier wrote: > Add a device link between the PWM consumer and the PWM provider. This > enforces the PWM user to get suspended before the PWM provider. It > allows proper synchronization of suspend/resume sequences: the PWM user > is responsible for properly stopping PWM, before the provider gets > suspended: see [1]. Add the device link in: > - pwm_get() > - devm_pwm_get() > - devm_of_pwm_get() > as it requires a reference to the device for the PWM consumer. > > [1] https://lkml.org/lkml/2019/2/5/770 > > Suggested-by: Thierry Reding <thierry.reding@xxxxxxxxx> > Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx> > --- > drivers/pwm/core.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..2835e27 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -770,8 +770,13 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) > int err; > > /* look up via DT first */ > - if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) > - return of_pwm_get(dev->of_node, con_id); > + if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) { > + pwm = of_pwm_get(dev->of_node, con_id); > + if (!IS_ERR(pwm)) > + device_link_add(dev, pwm->chip->dev, > + DL_FLAG_AUTOREMOVE_CONSUMER); > + return pwm; > + } > > /* > * We look up the provider in the static table typically provided by > @@ -851,6 +856,8 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) > pwm->args.period = chosen->period; > pwm->args.polarity = chosen->polarity; > > + device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER); > + > return pwm; > } > EXPORT_SYMBOL_GPL(pwm_get); > @@ -943,6 +950,8 @@ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np, > if (!IS_ERR(pwm)) { > *ptr = pwm; > devres_add(dev, ptr); > + device_link_add(dev, pwm->chip->dev, > + DL_FLAG_AUTOREMOVE_CONSUMER); IMHO it's surprising that devm_of_pwm_get() does more than of_pwm_get() + devres stuff. I'd put device_link_add() into of_pwm_get(). Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
