Date:   Fri, 10 Feb 2023 12:56:25 +0100
From:   Philipp Zabel <p.zabel@pengutronix.de>
To:     Peter Rosin <peda@axentia.se>
Cc:     Randy Dunlap <rdunlap@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mux: mmio: select REGMAP as the code has that dependency
Message-ID: <20230210115625.GA30942@pengutronix.de>
References: <64cf625b-2495-2382-0331-519d1cab0adf@infradead.org>
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 <89199aca-5b57-e8df-03ca-b2658ee9d8b3@axentia.se>
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On Fri, Feb 10, 2023 at 11:46:42AM +0100, Peter Rosin wrote:
> If CONFIG_REGMAP is not active, the build errors out like this:

The driver used to have an indirect dependency on CONFIG_REGMAP via
CONFIG_MFD_SYSCON -> CONFIG_REGMAP_MMIO -> CONFIG_REGMAP until
commit 8ecfaca7926f ("mux: mmio: add generic regmap bitfield-based
multiplexer").

> ../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;
>       |                                  ^~~~~
> 

Fixes: 8ecfaca7926f ("mux: mmio: add generic regmap bitfield-based multiplexer")

> Reported by: Randy Dunlap <rdunlap@infradead.org>
> Link: https://lore.kernel.org/lkml/64cf625b-2495-2382-0331-519d1cab0adf@infradead.org/
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  drivers/mux/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> Note, there is a patch in linux-next that removes "|| COMPILE_TEST" from depends.
> 
> Cheers,
> Peter
> 
> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
> index 80f015cf6e54..9234f8c400ca 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
> +	select REGMAP

I get a dependency loop with this:

drivers/net/ethernet/arc/Kconfig:19:error: recursive dependency detected!
drivers/net/ethernet/arc/Kconfig:19:symbol ARC_EMAC_CORE is selected by ARC_EMAC
drivers/net/ethernet/arc/Kconfig:26:symbol ARC_EMAC depends on OF_IRQ
drivers/of/Kconfig:69:symbol OF_IRQ depends on IRQ_DOMAIN
kernel/irq/Kconfig:60:symbol IRQ_DOMAIN is selected by REGMAP
drivers/base/regmap/Kconfig:6:symbol REGMAP is selected by MUX_MMIO
drivers/mux/Kconfig:48:symbol MUX_MMIO depends on MULTIPLEXER
drivers	/mux/Kconfig:6:symbol MULTIPLEXER is selected by MDIO_BUS_MUX_MULTIPLEXER
drivers/net/mdio/Kconfig:261:symbol MDIO_BUS_MUX_MULTIPLEXER depends on MDIO_DEVICE
drivers/net/mdio/Kconfig:6:symbol MDIO_DEVICE is selected by PHYLIB
drivers/net/phy/Kconfig:16:symbol PHYLIB is selected by ARC_EMAC_CORE

(on next-20230210).

regards
Philipp