On 2/18/19 6:22 PM, Uwe Kleine-König wrote: > 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, ...) ? Hi Uwe, I'm wondering a bit about this: In this case, the caller that doesn't provide a struct device *, PWM provider isn't responsible for that. So I just hope this wouldn't be miss-leading ? > >> + 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. Oops, I'll fix it. Thanks, Fabrice > >> + } >> + >> + return dl; >> +} >> + > > Best regards > Uwe >
