linux-kernel - Re: [PATCH v1] pinctrl: mpfs-iomux0: fix compile-time constant warning for LLVM prior to 17

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Message-ID: <20251029172036.GA1130586@ax162>
Date: Wed, 29 Oct 2025 10:20:36 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Conor Dooley <conor@...nel.org>
Cc: linux-gpio@...r.kernel.org, Conor Dooley <conor.dooley@...rochip.com>,
	Daire McNamara <daire.mcnamara@...rochip.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: Re: [PATCH v1] pinctrl: mpfs-iomux0: fix compile-time constant
 warning for LLVM prior to 17

On Wed, Oct 29, 2025 at 03:29:35PM +0000, Conor Dooley wrote:
> From: Conor Dooley <conor.dooley@...rochip.com>
> 
> With LLVM prior to 17.0.0:
> 
> drivers/pinctrl/pinctrl-mpfs-iomux0.c:89:2: error: initializer element is not a compile-time constant
>         MPFS_IOMUX0_GROUP(spi0),
>         ^~~~~~~~~~~~~~~~~~~~~~~
> drivers/pinctrl/pinctrl-mpfs-iomux0.c:79:10: note: expanded from macro 'MPFS_IOMUX0_GROUP'
>         .mask = BIT(mpfs_iomux0_##_name##_pins[0]),     \
>                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/vdso/bits.h:7:19: note: expanded from macro 'BIT'
> \#define BIT(nr)                 (UL(1) << (nr))
>                                 ^~~~~~~~~~~~~~~
> 
> This is a constant, but LLVM prior to a change from Nick to match the
> gcc behaviour did not allow this. The macro isn't really all that much
> of an idiot-proofing, just change it to the same sort that's in the
> gpio2 driver, where a second argument provides the mask/setting.
> 
> Reported-by: Nathan Chancellor <nathan@...nel.org>
> Link: https://github.com/ClangBuiltLinux/linux/issues/2140
> Fixes: 46397274da22 ("pinctrl: add polarfire soc iomux0 pinmux driver")
> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>

Thanks a lot for the quick fix!

Reviewed-by: Nathan Chancellor <nathan@...nel.org>

> ---
> 
> Not entirely sold on the fixes tag since it's to shut up an old
> compiler, but no harm in it I guess.
> 
> CC: Conor Dooley <conor.dooley@...rochip.com>
> CC: Daire McNamara <daire.mcnamara@...rochip.com>
> CC: Linus Walleij <linus.walleij@...aro.org>
> CC: Nathan Chancellor <nathan@...nel.org>
> CC: Nick Desaulniers <nick.desaulniers+lkml@...il.com>
> CC: Bill Wendling <morbo@...gle.com>
> CC: Justin Stitt <justinstitt@...gle.com>
> CC: linux-riscv@...ts.infradead.org
> CC: linux-gpio@...r.kernel.org
> CC: linux-kernel@...r.kernel.org
> CC: llvm@...ts.linux.dev
> ---
>  drivers/pinctrl/pinctrl-mpfs-iomux0.c | 36 +++++++++++++--------------
>  1 file changed, 18 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pinctrl/pinctrl-mpfs-iomux0.c b/drivers/pinctrl/pinctrl-mpfs-iomux0.c
> index 49d9fcec0a16..cf5b2e4e8f5b 100644
> --- a/drivers/pinctrl/pinctrl-mpfs-iomux0.c
> +++ b/drivers/pinctrl/pinctrl-mpfs-iomux0.c
> @@ -73,33 +73,33 @@ static const unsigned int mpfs_iomux0_uart4_pins[] = { 11 };
>  static const unsigned int mpfs_iomux0_mdio0_pins[] = { 12 };
>  static const unsigned int mpfs_iomux0_mdio1_pins[] = { 13 };
>  
> -#define MPFS_IOMUX0_GROUP(_name) { \
> +#define MPFS_IOMUX0_GROUP(_name, _mask) { \
>  	.name = #_name "_mssio",	\
>  	.pins = mpfs_iomux0_##_name##_pins,	\
> -	.mask = BIT(mpfs_iomux0_##_name##_pins[0]),	\
> +	.mask = _mask,	\
>  	.setting = 0x0,	\
>  }, { \
>  	.name = #_name "_fabric",	\
>  	.pins = mpfs_iomux0_##_name##_pins,	\
> -	.mask = BIT(mpfs_iomux0_##_name##_pins[0]),	\
> -	.setting = BIT(mpfs_iomux0_##_name##_pins[0]),	\
> +	.mask = _mask,	\
> +	.setting = _mask,	\
>  }
>  
>  static const struct mpfs_iomux0_pin_group mpfs_iomux0_pin_groups[] = {
> -	MPFS_IOMUX0_GROUP(spi0),
> -	MPFS_IOMUX0_GROUP(spi1),
> -	MPFS_IOMUX0_GROUP(i2c0),
> -	MPFS_IOMUX0_GROUP(i2c1),
> -	MPFS_IOMUX0_GROUP(can0),
> -	MPFS_IOMUX0_GROUP(can1),
> -	MPFS_IOMUX0_GROUP(qspi),
> -	MPFS_IOMUX0_GROUP(uart0),
> -	MPFS_IOMUX0_GROUP(uart1),
> -	MPFS_IOMUX0_GROUP(uart2),
> -	MPFS_IOMUX0_GROUP(uart3),
> -	MPFS_IOMUX0_GROUP(uart4),
> -	MPFS_IOMUX0_GROUP(mdio0),
> -	MPFS_IOMUX0_GROUP(mdio1),
> +	MPFS_IOMUX0_GROUP(spi0, BIT(0)),
> +	MPFS_IOMUX0_GROUP(spi1, BIT(1)),
> +	MPFS_IOMUX0_GROUP(i2c0, BIT(2)),
> +	MPFS_IOMUX0_GROUP(i2c1, BIT(3)),
> +	MPFS_IOMUX0_GROUP(can0, BIT(4)),
> +	MPFS_IOMUX0_GROUP(can1, BIT(5)),
> +	MPFS_IOMUX0_GROUP(qspi, BIT(6)),
> +	MPFS_IOMUX0_GROUP(uart0, BIT(7)),
> +	MPFS_IOMUX0_GROUP(uart1, BIT(8)),
> +	MPFS_IOMUX0_GROUP(uart2, BIT(9)),
> +	MPFS_IOMUX0_GROUP(uart3, BIT(10)),
> +	MPFS_IOMUX0_GROUP(uart4, BIT(11)),
> +	MPFS_IOMUX0_GROUP(mdio0, BIT(12)),
> +	MPFS_IOMUX0_GROUP(mdio1, BIT(13)),
>  };
>  
>  static const char * const mpfs_iomux0_spi0_groups[] = { "spi0_mssio", "spi0_fabric" };
> -- 
> 2.51.0
>