linux-kernel - Re: [PATCH v2] mux: mmio: depend on REGMAP as the code has that dependency

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Date:   Sun, 11 Jun 2023 13:59:29 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Peter Rosin <peda@...ntia.se>,
        Philipp Zabel <p.zabel@...gutronix.de>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mux: mmio: depend on REGMAP as the code has that
 dependency

Hi--

On 5/24/23 05:52, Peter Rosin wrote:
> If CONFIG_REGMAP is not active, the build errors out like this:
> 
> ../drivers/mux/mmio.c: In function ‘mux_mmio_probe’:
> ../drivers/mux/mmio.c:76:34: error: storage size of ‘field’ isn’t known
>    76 |                 struct reg_field field;
>       |                                  ^~~~~
> In file included from ../include/linux/bits.h:21,
>                  from ../include/linux/bitops.h:6,
>                  from ../drivers/mux/mmio.c:8:
> ../include/linux/bits.h:23:28: error: first argument to ‘__builtin_choose_expr’ not a constant
>    23 |         (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
>       |                            ^~~~~~~~~~~~~~~~~~~~~
> ../include/linux/build_bug.h:16:62: note: in definition of macro ‘BUILD_BUG_ON_ZERO’
>    16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
>       |                                                              ^
> ../include/linux/bits.h:37:10: note: in expansion of macro ‘GENMASK_INPUT_CHECK’
>    37 |         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
>       |          ^~~~~~~~~~~~~~~~~~~
> ../drivers/mux/mmio.c:96:29: note: in expansion of macro ‘GENMASK’
>    96 |                 if (mask != GENMASK(field.msb, field.lsb)) {
>       |                             ^~~~~~~
> ../include/linux/build_bug.h:16:51: error: bit-field ‘<anonymous>’ width not an integer constant
>    16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
>       |                                                   ^
> ../include/linux/bits.h:23:10: note: in expansion of macro ‘BUILD_BUG_ON_ZERO’
>    23 |         (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
>       |          ^~~~~~~~~~~~~~~~~
> ../include/linux/bits.h:37:10: note: in expansion of macro ‘GENMASK_INPUT_CHECK’
>    37 |         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
>       |          ^~~~~~~~~~~~~~~~~~~
> ../drivers/mux/mmio.c:96:29: note: in expansion of macro ‘GENMASK’
>    96 |                 if (mask != GENMASK(field.msb, field.lsb)) {
>       |                             ^~~~~~~
> ../drivers/mux/mmio.c:102:29: error: implicit declaration of function ‘devm_regmap_field_alloc’ [-Werror=implicit-function-declaration]
>   102 |                 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
>       |                             ^~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/mux/mmio.c:76:34: warning: unused variable ‘field’ [-Wunused-variable]
>    76 |                 struct reg_field field;
>       |                                  ^~~~~
> 
> REGMAP is normally "selected", but that causes a recursive dependency.
> But since REGMAP is "depended on" in other places, do so here as well.
> The (implicit) REGMAP dependency was lost when the strict dependency
> on MFD_SYSCON was removed.
> 
> Reported by: Randy Dunlap <rdunlap@...radead.org>
> Fixes: 8ecfaca7926f ("mux: mmio: add generic regmap bitfield-based multiplexer")
> Link: https://lore.kernel.org/lkml/64cf625b-2495-2382-0331-519d1cab0adf@infradead.org/
> Signed-off-by: Peter Rosin <peda@...ntia.se>
> ---
>  drivers/mux/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> Note, there is a patch in linux-next that removes "|| COMPILE_TEST" from the
> pre-existing depends.
> 
> Cheers,
> Peter
> 
> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
> index 80f015cf6e54..7f07ca06eb2b 100644
> --- a/drivers/mux/Kconfig
> +++ b/drivers/mux/Kconfig
> @@ -48,6 +48,7 @@ config MUX_GPIO
>  config MUX_MMIO
>  	tristate "MMIO/Regmap register bitfield-controlled Multiplexer"
>  	depends on OF
> +	depends on REGMAP

REGMAP is mostly selected, not depended on, so preferably

	select REGMAP

here whenever this patch is ready to be merged.

>  	help
>  	  MMIO/Regmap register bitfield-controlled Multiplexer controller.
>  

thanks.
-- 
~Randy