linux-kernel - Re: [PATCH] [v2] of: add more dummy helper functions

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Message-ID: <20200114235518.GA11575@bogus>
Date:   Tue, 14 Jan 2020 17:55:18 -0600
From:   Rob Herring <robh@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Jyri Sarha <jsarha@...com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] of: add more dummy helper functions

On Wed, Jan 08, 2020 at 02:49:28PM +0100, Arnd Bergmann wrote:
> The new phy-j721e-wiz driver causes a link failure without CONFIG_OF:
> 
> drivers/phy/ti/phy-j721e-wiz.o: In function `wiz_remove':
> phy-j721e-wiz.c:(.text+0x40): undefined reference to `of_platform_device_destroy'
> 
> Add a dummy version of of_platform_device_destroy to avoid having to add
> Kconfig dependencies for the driver. As there are a few other functions
> without dummy implementations, add those as well for completeness.
> 
> Fixes: 42440de5438a ("phy: ti: j721e-wiz: Add support for WIZ module present in TI J721E SoC")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  include/linux/of_platform.h | 39 ++++++++++++++++++++++++++++---------
>  1 file changed, 30 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
> index 84a966623e78..f5dea3de4856 100644
> --- a/include/linux/of_platform.h
> +++ b/include/linux/of_platform.h
> @@ -48,28 +48,49 @@ struct of_dev_auxdata {
>  
>  extern const struct of_device_id of_default_bus_match_table[];
>  
> +#ifdef CONFIG_OF
>  /* Platform drivers register/unregister */
>  extern struct platform_device *of_device_alloc(struct device_node *np,
>  					 const char *bus_id,
>  					 struct device *parent);
> -#ifdef CONFIG_OF
>  extern struct platform_device *of_find_device_by_node(struct device_node *np);
> -#else
> -static inline struct platform_device *of_find_device_by_node(struct device_node *np)
> -{
> -	return NULL;
> -}
> -#endif
> -
>  /* Platform devices and busses creation */
>  extern struct platform_device *of_platform_device_create(struct device_node *np,
>  						   const char *bus_id,
>  						   struct device *parent);
> -
>  extern int of_platform_device_destroy(struct device *dev, void *data);
>  extern int of_platform_bus_probe(struct device_node *root,
>  				 const struct of_device_id *matches,
>  				 struct device *parent);
> +#else
> +static inline struct platform_device *of_device_alloc(struct device_node *np,
> +						      const char *bus_id,
> +						      struct device *parent)
> +{
> +	return NULL;
> +}
> +static inline struct platform_device *of_find_device_by_node(struct device_node *np)
> +{
> +	return NULL;
> +}
> +static inline struct platform_device *of_platform_device_create(struct device_node *np,
> +								const char *bus_id,
> +								struct device *parent)
> +{
> +	return NULL;
> +}
> +static inline int of_platform_device_destroy(struct device *dev, void *data)
> +{
> +	return 0;
> +}
> +static inline int of_platform_bus_probe(struct device_node *root,
> +					const struct of_device_id *matches,
> +					struct device *parent)
> +{
> +	return -ENODEV;
> +}

This and of_device_alloc are pretty much only powerpc functions, so I 
want things to break if there are new users. There's one user of 
of_device_alloc() and a couple for of_platform_bus_probe() which is 
deprecated in favor of of_platform_populate(). I think we can get rid of 
the remaining x86 callers.

(I have the same opinion on of_platform_device_create too, but I've 
given up on that).

Rob