Re: iomux-mx3.h: possible macro precedence issue

From	Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Newsgroups	linux.kernel
Subject	Re: iomux-mx3.h: possible macro precedence issue
Date	2016-09-21 08:10 +0200
Message-ID	<sjITg-5i1-9@gated-at.bofh.it> (permalink)
References	<sjzwC-7F4-33@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Cc += Shawn

Hello,

On Tue, Sep 20, 2016 at 01:02:24PM -0700, Joe Perches wrote:
> Julia Lawall wrote a script
> 
> Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1609201503260.2914@hadrien
> 
> that found a possible issue with macro argument precedence.
> 
> 
> diff -u -p a/arch/arm/mach-imx/iomux-mx3.h b/arch/arm/mach-imx/iomux-mx3.h
> --- a/arch/arm/mach-imx/iomux-mx3.h
> +++ b/arch/arm/mach-imx/iomux-mx3.h
> @@ -529,7 +529,7 @@ enum iomux_pins {
>  #define MX31_PIN_DCD_DTE1__DCD_DTE2	IOMUX_MODE(MX31_PIN_DCD_DTE1, IOMUX_CONFIG_ALT1)
>  #define MX31_PIN_RI_DTE1__RI_DTE2	IOMUX_MODE(MX31_PIN_RI_DTE1, IOMUX_CONFIG_ALT1)
>  #define MX31_PIN_DSR_DTE1__DSR_DTE2	IOMUX_MODE(MX31_PIN_DSR_DTE1, IOMUX_CONFIG_ALT1)
> -#define MX31_PIN_DTR_DTE1__DTR_DTE2	IOMUX_MODE(MX31_PIN_DTR_DTE1, IOMUX_OCONFIG_ALT3 | IOMUX_ICONFIG_NONE)
> +#define MX31_PIN_DTR_DTE1__DTR_DTE2	IOMUX_MODE(MX31_PIN_DTR_DTE1, (IOMUX_OCONFIG_ALT3 | IOMUX_ICONFIG_NONE))
>  #define MX31_PIN_PC_RST__CTS5		IOMUX_MODE(MX31_PIN_PC_RST, IOMUX_CONFIG_ALT2)
>  #define MX31_PIN_PC_VS2__RTS5		IOMUX_MODE(MX31_PIN_PC_VS2, IOMUX_CONFIG_ALT2)
>  #define MX31_PIN_PC_BVD2__TXD5		IOMUX_MODE(MX31_PIN_PC_BVD2, IOMUX_CONFIG_ALT2)

I assume this is the only problematic definition? If so, there is a
single affected platform: arch/arm/mach-imx/mach-kzm_arm11_01.c
 
> this may be intentional, but perhaps a solution
> would be to use parentheses in the #define IOMUX_MODE 
> 
> ---
> 
> diff --git a/arch/arm/mach-imx/iomux-mx3.h b/arch/arm/mach-imx/iomux-mx3.h
> index 368667b..3f9ede2 100644
> --- a/arch/arm/mach-imx/iomux-mx3.h
> +++ b/arch/arm/mach-imx/iomux-mx3.h
> @@ -156,7 +156,7 @@ void mxc_iomux_mode(unsigned int pin_mode);
>  	(((gpionum << IOMUX_GPIONUM_SHIFT) & IOMUX_GPIONUM_MASK) | \
>  	 (padnum & IOMUX_PADNUM_MASK))
>  
> -#define IOMUX_MODE(pin, mode) (pin | mode << IOMUX_MODE_SHIFT)
> +#define IOMUX_MODE(pin, mode) ((pin) | ((mode) << IOMUX_MODE_SHIFT))
>  
>  #define IOMUX_TO_GPIO(iomux_pin) \
>  	((iomux_pin & IOMUX_GPIONUM_MASK) >> IOMUX_GPIONUM_SHIFT)

My preference is to fix IOMUX_MODE instead of adding the parents to
MX31_PIN_DTR_DTE1__DTR_DTE2.

Joe, do you create a proper patch?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Thread

iomux-mx3.h: possible macro precedence issue Joe Perches <joe@perches.com> - 2016-09-20 22:10 +0200
  Re: iomux-mx3.h: possible macro precedence issue Uwe Kleine-König          <u.kleine-koenig@pengutronix.de> - 2016-09-21 08:10 +0200
    Re: iomux-mx3.h: possible macro precedence issue Joe Perches <joe@perches.com> - 2016-09-21 08:20 +0200
      Re: iomux-mx3.h: possible macro precedence issue Uwe Kleine-König          <u.kleine-koenig@pengutronix.de> - 2016-09-21 08:50 +0200

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