Re: [PATCH 2/6] mfd: hi6421-pmic: move hi6421_regmap_config definition to header file

[Arnd Bergmann <arnd@arndb.de>]

On Fri, May 26, 2017 at 8:35 AM, Guodong Xu <guodong.xu@linaro.org> wrote:
> Move hi6421_regmap_config definition from c code to common header:
>  - include/linux/mfd/hi6421-pmic.h
>
> This is to improve code re-use for upcoming hi6421 series of MFD driver.
>
> Signed-off-by: Guodong Xu <guodong.xu@linaro.org>

> diff --git a/include/linux/mfd/hi6421-pmic.h b/include/linux/mfd/hi6421-pmic.h
> index 587273e..f4674ff 100644
> --- a/include/linux/mfd/hi6421-pmic.h
> +++ b/include/linux/mfd/hi6421-pmic.h
> @@ -38,4 +38,10 @@ struct hi6421_pmic {
>         struct regmap           *regmap;
>  };
>
> +static const struct regmap_config hi6421_regmap_config = {
> +       .reg_bits = 32,
> +       .reg_stride = 4,
> +       .val_bits = 8,
> +       .max_register = HI6421_REG_TO_BUS_ADDR(HI6421_REG_MAX),
> +};
>  #endif         /* __HI6421_PMIC_H */

Header files should not have static variables in general, it will cause warnings
about unused variables when you include the header from another file
(depending on compiler version and warning options, I think older gcc
versions don't warn about this, but clang and latest gcc do).

How about adding the new code into the existing
drivers/mfd/hi6421-pmic-core.c file, and splitting out the part that differs
(the regmap_update_bits is the only difference I see) into a callback
that you reference through the of_device_id->data pointer?

        Arnd