Hello, On Thu, Feb 14, 2019 at 11:25:51AM +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: > - of_pwm_get() > - pwm_get() > - devm_*pwm_get() 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 v4: > - rework error handling following Thierry's comments > - turn/split pr_debug() into dev_err()/pr_warn(). > > Changes in v3: > - add struct device to of_get_pwm() arguments to handle device link from > there as discussed with Uwe. > --- > drivers/pwm/core.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++--- > include/linux/pwm.h | 6 ++++-- > 2 files changed, 51 insertions(+), 5 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..64e10a6 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -636,8 +636,35 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) > return ERR_PTR(-EPROBE_DEFER); > } > > +static struct device_link *pwm_device_link_add(struct device *dev, > + struct pwm_device *pwm) > +{ > + struct device_link *dl; > + > + if (!dev) { > + /* > + * No device for the PWM consumer has been provided. It may > + * impact the PM sequence ordering: the PWM supplier may get > + * suspended before the consumer. > + */ > + pr_warn("no consumer dev, can't create device link to %s\n", > + dev_name(pwm->chip->dev)); Maybe use dev_warn(pwm->chip->dev, ...) ? > + return NULL; > + } > + > + dl = device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER); > + if (!dl) { > + dev_err(dev, "failed to create device link to %s\n", > + dev_name(pwm->chip->dev)); > + return ERR_PTR(-EINVAL); broken indention. > + } > + > + return dl; > +} > + Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
