[v2,2/7] usb: typec: mux: Add CONFIG guards for functions

There are some drivers that can use the Type C mux API, but don't have
to. Introduce CONFIG guards for the mux functions so that drivers can
include the header file and not run into compilation errors on systems
which don't have CONFIG_TYPEC enabled. When CONFIG_TYPEC is not enabled,
the Type C mux functions will be stub versions of the original calls.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
---

Changes since v1:
- Added static inline to stub functions.
- Updated function signature of stub functions from "struct typec_mux"
  to "struct typec_mux_dev" in accordance with updates from commit
  713fd49b430c ("usb: typec: mux: Introduce indirection")

 include/linux/usb/typec_mux.h | 38 +++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

Hi,

On Thu, Jun 09, 2022 at 06:09:41PM +0000, Prashant Malani wrote:
> There are some drivers that can use the Type C mux API, but don't have
> to. Introduce CONFIG guards for the mux functions so that drivers can
> include the header file and not run into compilation errors on systems
> which don't have CONFIG_TYPEC enabled. When CONFIG_TYPEC is not enabled,
> the Type C mux functions will be stub versions of the original calls.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Prashant Malani <pmalani@chromium.org>
> ---
> 
> Changes since v1:
> - Added static inline to stub functions.
> - Updated function signature of stub functions from "struct typec_mux"
>   to "struct typec_mux_dev" in accordance with updates from commit
>   713fd49b430c ("usb: typec: mux: Introduce indirection")
> 
>  include/linux/usb/typec_mux.h | 38 +++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/include/linux/usb/typec_mux.h b/include/linux/usb/typec_mux.h
> index ee57781dcf28..9eda6146fd26 100644
> --- a/include/linux/usb/typec_mux.h
> +++ b/include/linux/usb/typec_mux.h
> @@ -58,6 +58,8 @@ struct typec_mux_desc {
>  	void *drvdata;
>  };
>  
> +#if IS_ENABLED(CONFIG_TYPEC) || IS_MODULE(CONFIG_TYPEC)
> +
>  struct typec_mux *fwnode_typec_mux_get(struct fwnode_handle *fwnode,
>  				       const struct typec_altmode_desc *desc);
>  void typec_mux_put(struct typec_mux *mux);
> @@ -76,4 +78,40 @@ void typec_mux_unregister(struct typec_mux_dev *mux);
>  void typec_mux_set_drvdata(struct typec_mux_dev *mux, void *data);
>  void *typec_mux_get_drvdata(struct typec_mux_dev *mux);
>  
> +#else
> +
> +static inline struct typec_mux *fwnode_typec_mux_get(struct fwnode_handle *fwnode,
> +				       const struct typec_altmode_desc *desc)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}

The mux is optional resource for the drivers - fwnode_typec_mux_get()
returns NULL if there is no mux for the caller - so it's better to
just return NULL from this stub.

> +static inline void typec_mux_put(struct typec_mux *mux) {}
> +
> +static inline int typec_mux_set(struct typec_mux *mux, struct typec_mux_state *state)
> +{
> +	return -EOPNOTSUPP;
> +}

Return 0 in this case. That way this stub matches the function
behaviour:

        ...
        if (IS_ERR_OR_NULL(mux))
                return 0;
        ...

> +static inline struct typec_mux *
> +typec_mux_get(struct device *dev, const struct typec_altmode_desc *desc)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}

You don't need this one. Just leave the original outside of the ifdef.
It's already an inline wrapper function.

> +static inline struct typec_mux_dev *
> +typec_mux_register(struct device *parent, const struct typec_mux_desc *desc)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +static inline void typec_mux_unregister(struct typec_mux_dev *mux) {}
> +
> +static inline void typec_mux_set_drvdata(struct typec_mux_dev *mux, void *data) {}
> +static inline void *typec_mux_get_drvdata(struct typec_mux_dev *mux)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +#endif /* CONFIG_TYPEC */
> +
>  #endif /* __USB_TYPEC_MUX */

thanks,

Il 09/06/22 20:09, Prashant Malani ha scritto:
> There are some drivers that can use the Type C mux API, but don't have
> to. Introduce CONFIG guards for the mux functions so that drivers can
> include the header file and not run into compilation errors on systems
> which don't have CONFIG_TYPEC enabled. When CONFIG_TYPEC is not enabled,
> the Type C mux functions will be stub versions of the original calls.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Prashant Malani <pmalani@chromium.org>
> ---
> 
> Changes since v1:
> - Added static inline to stub functions.
> - Updated function signature of stub functions from "struct typec_mux"
>    to "struct typec_mux_dev" in accordance with updates from commit
>    713fd49b430c ("usb: typec: mux: Introduce indirection")
> 
>   include/linux/usb/typec_mux.h | 38 +++++++++++++++++++++++++++++++++++
>   1 file changed, 38 insertions(+)
> 
> diff --git a/include/linux/usb/typec_mux.h b/include/linux/usb/typec_mux.h
> index ee57781dcf28..9eda6146fd26 100644
> --- a/include/linux/usb/typec_mux.h
> +++ b/include/linux/usb/typec_mux.h
> @@ -58,6 +58,8 @@ struct typec_mux_desc {
>   	void *drvdata;
>   };
>   
> +#if IS_ENABLED(CONFIG_TYPEC) || IS_MODULE(CONFIG_TYPEC)

IS_ENABLED(x) evaluates to 1 when (x == 'y' || x == 'm')
IS_MODULE(x) evaluates to 1 when              (x == 'm')

....this means that a IS_ENABLED(CONFIG_TYPEC) check is enough, and
the latter is redundant.

Regards,
Angelo