Message ID | 1550139951-25788-1-git-send-email-fabrice.gasnier@st.com |
---|---|
Headers | show |
Series | Add PM support to STM32 LP Timer drivers | expand |
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@gmail.com> > Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> > --- > 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
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@gmail.com> >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >> --- >> 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 >
On Tue, Feb 19, 2019 at 09:46:32AM +0100, Fabrice Gasnier wrote: > 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@gmail.com> > >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> > >> --- > >> 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 ? IMHO it's more the wording that might make the message misleading. If you use dev_warn(pwm->chip->dev, "No consumer device specified to create a device link to\n"); that's completely fine in my eyes. Best regards Uwe
On 2/19/19 9:55 AM, Uwe Kleine-König wrote: > On Tue, Feb 19, 2019 at 09:46:32AM +0100, Fabrice Gasnier wrote: >> 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@gmail.com> >>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >>>> --- >>>> 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 ? > > IMHO it's more the wording that might make the message misleading. If > you use > > dev_warn(pwm->chip->dev, "No consumer device specified to create a device link to\n"); > > that's completely fine in my eyes. Thanks for the suggestion, I'll update this as well in v5. Best regards, Fabrice > > Best regards > Uwe >