On 13.02.2019 12:50, 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: > - of_pwm_get() > - pwm_get() > - devm_ variants > 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> > --- > Changes in v3: > - add struct device to of_get_pwm() arguments to handle device link from > there. > --- > drivers/pwm/core.c | 14 +++++++++++--- > include/linux/pwm.h | 6 ++++-- > 2 files changed, 15 insertions(+), 5 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..8cb5d4bc 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -638,6 +638,7 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) > > /** > * of_pwm_get() - request a PWM via the PWM framework > + * @dev: device for PWM consumer > * @np: device node to get the PWM from > * @con_id: consumer name > * > @@ -655,7 +656,8 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) > * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded > * error code on failure. > */ > -struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id) > +struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np, > + const char *con_id) > { > struct pwm_device *pwm = NULL; > struct of_phandle_args args; > @@ -689,6 +691,9 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id) > if (IS_ERR(pwm)) > goto put; > > + if (!device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) > + pr_debug("%s(): device link not added\n", __func__); > + Just asking... will this mechanism also be working for PWMs requested via sysfs? At a first look it seems not. Thank you, Claudiu Beznea > /* > * If a consumer name was not given, try to look it up from the > * "pwm-names" property if it exists. Otherwise use the name of > @@ -771,7 +776,7 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) > > /* look up via DT first */ > if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) > - return of_pwm_get(dev->of_node, con_id); > + return of_pwm_get(dev, dev->of_node, con_id); > > /* > * We look up the provider in the static table typically provided by > @@ -851,6 +856,9 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) > pwm->args.period = chosen->period; > pwm->args.polarity = chosen->polarity; > > + if (!device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) > + pr_debug("%s(): device link not added\n", __func__); > + > return pwm; > } > EXPORT_SYMBOL_GPL(pwm_get); > @@ -939,7 +947,7 @@ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np, > if (!ptr) > return ERR_PTR(-ENOMEM); > > - pwm = of_pwm_get(np, con_id); > + pwm = of_pwm_get(dev, np, con_id); > if (!IS_ERR(pwm)) { > *ptr = pwm; > devres_add(dev, ptr); > diff --git a/include/linux/pwm.h b/include/linux/pwm.h > index d5199b5..895e074 100644 > --- a/include/linux/pwm.h > +++ b/include/linux/pwm.h > @@ -406,7 +406,8 @@ struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc, > const struct of_phandle_args *args); > > struct pwm_device *pwm_get(struct device *dev, const char *con_id); > -struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id); > +struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np, > + const char *con_id); > void pwm_put(struct pwm_device *pwm); > > struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id); > @@ -494,7 +495,8 @@ static inline struct pwm_device *pwm_get(struct device *dev, > return ERR_PTR(-ENODEV); > } > > -static inline struct pwm_device *of_pwm_get(struct device_node *np, > +static inline struct pwm_device *of_pwm_get(struct device *dev, > + struct device_node *np, > const char *con_id) > { > return ERR_PTR(-ENODEV); >
