linux-kernel - Re: [PATCH] rtc-pcf2123: use sign

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Date:	Wed, 20 Apr 2016 00:44:43 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Martin Kepplinger <martink@...teo.de>
Cc:	a.zummo@...ertech.it, rtc-linux@...glegroups.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc-pcf2123: use sign_extend32() for sign extension

Please always include a commit message else, I'm fine with the patch.

On 18/04/2016 at 12:17:44 +0200, Martin Kepplinger wrote :
> Signed-off-by: Martin Kepplinger <martink@...teo.de>
> ---
>  drivers/rtc/rtc-pcf2123.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-pcf2123.c b/drivers/rtc/rtc-pcf2123.c
> index f22e060..b4478cc 100644
> --- a/drivers/rtc/rtc-pcf2123.c
> +++ b/drivers/rtc/rtc-pcf2123.c
> @@ -96,7 +96,7 @@
>  #define CD_TMR_TE		BIT(3)	/* Countdown timer enable */
>  
>  /* PCF2123_REG_OFFSET BITS */
> -#define OFFSET_SIGN_BIT		BIT(6)	/* 2's complement sign bit */
> +#define OFFSET_SIGN_BIT		6	/* 2's complement sign bit */
>  #define OFFSET_COARSE		BIT(7)	/* Coarse mode offset */
>  #define OFFSET_STEP		(2170)	/* Offset step in parts per billion */
>  
> @@ -217,7 +217,7 @@ static int pcf2123_read_offset(struct device *dev, long *offset)
>  	if (reg & OFFSET_COARSE)
>  		reg <<= 1; /* multiply by 2 and sign extend */
>  	else
> -		reg |= (reg & OFFSET_SIGN_BIT) << 1; /* sign extend only */
> +		reg = sign_extend32(reg, OFFSET_SIGN_BIT);
>  
>  	*offset = ((long)reg) * OFFSET_STEP;
>  
> -- 
> 2.1.4
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com