Re: [PATCH V2 4/4] pinctrl: add one more "const" for generic function groups

[Nathan Chancellor <nathan@xxxxxxxxxx>]

Hi Rafał,

On Thu, Dec 16, 2021 at 05:22:06PM +0100, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@xxxxxxxxxx>
> 
> Generic code doesn't modify those strings and .get_function_groups
> callback has that extra "const" as well. This allows more flexibility in
> GENERIC_PINMUX_FUNCTIONS users.
> 
> Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
> ---
>  drivers/pinctrl/pinmux.c | 2 +-
>  drivers/pinctrl/pinmux.h | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
> index 6cdbd9ccf2f0..f94d43b082d9 100644
> --- a/drivers/pinctrl/pinmux.c
> +++ b/drivers/pinctrl/pinmux.c
> @@ -875,7 +875,7 @@ EXPORT_SYMBOL_GPL(pinmux_generic_get_function);
>   */
>  int pinmux_generic_add_function(struct pinctrl_dev *pctldev,
>  				const char *name,
> -				const char **groups,
> +				const char * const *groups,
>  				const unsigned int num_groups,
>  				void *data)
>  {
> diff --git a/drivers/pinctrl/pinmux.h b/drivers/pinctrl/pinmux.h
> index 78c3a31be882..72fcf03eaa43 100644
> --- a/drivers/pinctrl/pinmux.h
> +++ b/drivers/pinctrl/pinmux.h
> @@ -129,7 +129,7 @@ static inline void pinmux_init_device_debugfs(struct dentry *devroot,
>   */
>  struct function_desc {
>  	const char *name;
> -	const char **group_names;
> +	const char * const *group_names;
>  	int num_group_names;
>  	void *data;
>  };
> @@ -150,7 +150,7 @@ struct function_desc *pinmux_generic_get_function(struct pinctrl_dev *pctldev,
>  
>  int pinmux_generic_add_function(struct pinctrl_dev *pctldev,
>  				const char *name,
> -				const char **groups,
> +				const char * const *groups,
>  				unsigned const num_groups,
>  				void *data);
>  
> -- 
> 2.31.1
> 
> 

I have not seen this reported yet, even though it has been broken for a
couple of weeks now. I see the following error in -next:

$ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- allmodconfig drivers/pinctrl/pinctrl-thunderbay.o
drivers/pinctrl/pinctrl-thunderbay.c: In function ‘thunderbay_add_functions’:
drivers/pinctrl/pinctrl-thunderbay.c:815:29: error: assignment discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
  815 |                         grp = func->group_names;
      |                             ^
cc1: all warnings being treated as errors

Looks like something like the third patch of the series is needed for
the Thunderbay driver, which it appears was in development at the same
time as this series.

Cheers,
Nathan