Messages in this thread | | | Subject | Re: [PATCH] reset: Make optional functions really optional. | From | Philipp Zabel <> | Date | Fri, 23 Dec 2016 13:08:54 +0100 |
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Hi Laurent,
Am Freitag, den 23.12.2016, 13:23 +0200 schrieb Laurent Pinchart: > Hello, > > On Friday 23 Dec 2016 11:58:57 Philipp Zabel wrote: > > Am Donnerstag, den 15.12.2016, 18:05 +0000 schrieb Ramiro Oliveira: > > > Up until now optional functions in the reset API were similar to the non > > > optional. > > > > > > This patch corrects that, while maintaining compatibility with existing > > > drivers. > > > > > > As suggested here: https://lkml.org/lkml/2016/12/14/502 > > > > > > Signed-off-by: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com> > > > --- > > > > > > drivers/reset/core.c | 21 +++++++++++++++++++-- > > > include/linux/reset.h | 46 ++++++++++++++++++++++++++++++++++++++++++---- > > > 2 files changed, 61 insertions(+), 6 deletions(-) > > > > > > diff --git a/drivers/reset/core.c b/drivers/reset/core.c > > > index 395dc9c..6150e7c 100644 > > > --- a/drivers/reset/core.c > > > +++ b/drivers/reset/core.c > > > @@ -135,9 +135,14 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register); > > > * @rstc: reset controller > > > * > > > * Calling this on a shared reset controller is an error. > > > + * > > > + * If it's an optional reset it will return 0. > > > > I'd prefer this to explicitly mention that rstc==NULL means this is an > > optional reset: > > > > "If rstc is NULL it is an optional reset and the function will just > > return 0." > > Maybe we should document in a single place that NULL is a valid value for a > reset_control pointer and will result in the API behaving as a no-op ? If you > want to duplicate the information I'd still prefer talking about no-op than > about "just returning 0".
Does "no-op" implicate the return value 0? Maybe there is a better way to express "no action, returns 0".
Currently there is no central place for this information, and as long as the text not much longer than a reference to the central location would be, I'm fine with duplication.
> > > */ > > > int reset_control_reset(struct reset_control *rstc) > > > { > > > + if (!rstc) > > > + return 0; > > > + > > > if (WARN_ON(rstc->shared)) > > > return -EINVAL; > > > > > > @@ -158,9 +163,14 @@ EXPORT_SYMBOL_GPL(reset_control_reset); > > > * > > > * For shared reset controls a driver cannot expect the hw's registers > > > and > > > * internal state to be reset, but must be prepared for this to happen. > > > + * > > > + * If it's an optional reset it will return 0. > > > > Same as above. > > > > > */ > > > > > > int reset_control_assert(struct reset_control *rstc) > > > { > > > + if (!rstc) > > > + return 0; > > > + > > > if (!rstc->rcdev->ops->assert) > > > return -ENOTSUPP; > > > > > > @@ -180,10 +190,14 @@ EXPORT_SYMBOL_GPL(reset_control_assert); > > > * reset_control_deassert - deasserts the reset line > > > * @rstc: reset controller > > > * > > > - * After calling this function, the reset is guaranteed to be deasserted. > > > + * After calling this function, the reset is guaranteed to be deasserted, > > > if > > > + * it's not optional. > > > > Same as above. > > > > > */ > > > int reset_control_deassert(struct reset_control *rstc) > > > { > > > + if (!rstc) > > > + return 0; > > > + > > > if (!rstc->rcdev->ops->deassert) > > > return -ENOTSUPP; > > > > > > @@ -199,11 +213,14 @@ EXPORT_SYMBOL_GPL(reset_control_deassert); > > > /** > > > * reset_control_status - returns a negative errno if not supported, a > > > * positive value if the reset line is asserted, or zero if the reset > > > - * line is not asserted. > > > + * line is not asserted or if the desc is NULL (optional reset). > > > * @rstc: reset controller > > > */ > > > int reset_control_status(struct reset_control *rstc) > > > { > > > + if (!rstc) > > > + return 0; > > > + > > > if (rstc->rcdev->ops->status) > > > return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); > > > > > > diff --git a/include/linux/reset.h b/include/linux/reset.h > > > index 5daff15..1af1e62 100644 > > > --- a/include/linux/reset.h > > > +++ b/include/linux/reset.h > > > @@ -138,13 +138,33 @@ static inline struct reset_control > > > *reset_control_get_shared(> > > > static inline struct reset_control *reset_control_get_optional_exclusive( > > > struct device *dev, const char *id) > > > { > > > - return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0); > > > + struct reset_control *desc; > > > + > > > + desc = __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 0); > > > > Note that the __of_reset_control_get stub returns -ENOTSUPP if > > CONFIG_RESET_CONTROLLER is disabled. > > > > > + if (IS_ERR(desc)) { > > > + if (PTR_ERR(desc) == -ENOENT) > > > + return NULL; > > > + } > > > + > > > + return desc; > > > + > > > } > > > > > > static inline struct reset_control *reset_control_get_optional_shared( > > > struct device *dev, const char *id) > > > { > > > - return __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 1); > > > + > > > + struct reset_control *desc; > > > + > > > + desc = __of_reset_control_get(dev ? dev->of_node : NULL, id, 0, 1); > > > + > > > + if (IS_ERR(desc)) { > > > + if (PTR_ERR(desc) == -ENOENT) > > > + return NULL; > > > + } > > > > With this duplication, I think it might be better to add an int optional > > parameter > > What's wrong with bool by the way ? :-)
Nothing wrong, it's just that the "exclusive" parameter is already int. I'd be perfectly fine with using bool for both.
regards Philipp
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