linux-kernel - Re: [PATCH v2 1/1] mux: consumer: Add dummy functions for !CONFIG

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Date:   Sun, 9 Jul 2017 00:22:47 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Peter Rosin <peda@...ntia.se>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sathyanarayanan Kuppuswamy Natarajan <sathyaosid@...il.com>
Subject: Re: [PATCH v2 1/1] mux: consumer: Add dummy functions for
 !CONFIG_MULTIPLEXER case

On Sat, Jul 8, 2017 at 9:12 PM,
<sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>
> Add dummy functions to avoid compile time issues when CONFIG_MULTIPLEXER
> is not enabled.
>

I don't think the error return code is okay to all of them. The return
value should be choosen carefully (for some functions it's okay IMO to
return 0).

> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> ---
>  include/linux/mux/consumer.h | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> Changes since v1:
>  * Changed #ifdef to #if IS_ENABLED.
>
> diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
> index 5577e1b..df78988 100644
> --- a/include/linux/mux/consumer.h
> +++ b/include/linux/mux/consumer.h
> @@ -16,6 +16,7 @@
>  struct device;
>  struct mux_control;
>
> +#if IS_ENABLED(CONFIG_MULTIPLEXER)
>  unsigned int mux_control_states(struct mux_control *mux);
>  int __must_check mux_control_select(struct mux_control *mux,
>                                     unsigned int state);
> @@ -29,4 +30,41 @@ void mux_control_put(struct mux_control *mux);
>  struct mux_control *devm_mux_control_get(struct device *dev,
>                                          const char *mux_name);
>
> +#else
> +unsigned int mux_control_states(struct mux_control *mux)
> +{
> +       return -ENODEV;

Peter, is here we are obliged to return error code in such case?

> +}
> +
> +int __must_check mux_control_select(struct mux_control *mux,
> +                                   unsigned int state)
> +{
> +       return -ENODEV;

return 0; ?

> +}
> +
> +int __must_check mux_control_try_select(struct mux_control *mux,
> +                                       unsigned int state)
> +{
> +       return -ENODEV;
> +}

return 0; ?

> +
> +int mux_control_deselect(struct mux_control *mux)
> +{
> +       return -ENODEV;
> +}

return 0; ?

> +
> +struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
> +{
> +       return ERR_PTR(-ENODEV);
> +}
> +
> +void mux_control_put(struct mux_control *mux) {}
> +
> +struct mux_control *devm_mux_control_get(struct device *dev,
> +                                        const char *mux_name)
> +{
> +       return ERR_PTR(-ENODEV);
> +}
> +#endif
> +
>  #endif /* _LINUX_MUX_CONSUMER_H */
> --
> 2.7.4
>



-- 
With Best Regards,
Andy Shevchenko