linux-kernel - Re: [PATCH linux-next v2] ASoC: adau1373: adau1373_hw

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Message-ID: <513E2FF0.1000608@metafoo.de>
Date:	Mon, 11 Mar 2013 20:26:40 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Tim Gardner <tim.gardner@...onical.com>
CC:	linux-kernel@...r.kernel.org, Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	device-drivers-devel@...ckfin.uclinux.org,
	alsa-devel@...a-project.org
Subject: Re: [PATCH linux-next v2] ASoC: adau1373: adau1373_hw_params: Silence
 overflow warning

On 03/11/2013 08:18 PM, Tim Gardner wrote:
> ADAU1373_BCLKDIV_SOURCE is defined as BIT(5) which uses UL constants. On
> amd64 the result of the ones complement operator is then truncated to
> unsigned int according to the prototype of snd_soc_update_bits(). I think
> gcc is correctly warning that the upper 32 bits are lost.
> 
> sound/soc/codecs/adau1373.c: In function 'adau1373_hw_params':
> sound/soc/codecs/adau1373.c:940:3: warning: large integer implicitly truncated to unsigned type [-Woverflow]
> 
> gcc version 4.6.3
> 
> Add 2 more BCLKDIV mask macros as explained by Lars:
> 
> The BCLKDIV has three fields. The bitclock divider (bit 0-1), the samplerate
> (bit 2-4) and the source select (bit 5). Here we want to update the bitclock
> divider field and the samplerate field. When I wrote the code I was lazy and
> used ~ADAU1373_BCLKDIV_SOURCE as the mask, which for this register is
> functionally equivalent to ADAU1373_BCLKDIV_SR_MASK | ADAU1373_BCLKDIV_BCLK_MASK.
> 
> Cc: Lars-Peter Clausen <lars@...afoo.de>
> Cc: Liam Girdwood <lgirdwood@...il.com>
> Cc: Mark Brown <broonie@...nsource.wolfsonmicro.com>
> Cc: Jaroslav Kysela <perex@...ex.cz>
> Cc: Takashi Iwai <tiwai@...e.de>
> Cc: device-drivers-devel@...ckfin.uclinux.org
> Cc: alsa-devel@...a-project.org
> Signed-off-by: Tim Gardner <tim.gardner@...onical.com>

Acked-by: Lars-Peter Clausen <lars@...afoo.de>

Thanks.

> ---
> v1 - simple cast solution
> v2 - Implement a full set of field masks as suggested by Lars.
> 
>  sound/soc/codecs/adau1373.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/soc/codecs/adau1373.c b/sound/soc/codecs/adau1373.c
> index 068b3ae..1aa10dd 100644
> --- a/sound/soc/codecs/adau1373.c
> +++ b/sound/soc/codecs/adau1373.c
> @@ -133,6 +133,8 @@ struct adau1373 {
>  #define ADAU1373_DAI_FORMAT_DSP		0x3
>  
>  #define ADAU1373_BCLKDIV_SOURCE		BIT(5)
> +#define ADAU1373_BCLKDIV_SR_MASK	(0x07 << 2)
> +#define ADAU1373_BCLKDIV_BCLK_MASK	0x03
>  #define ADAU1373_BCLKDIV_32		0x03
>  #define ADAU1373_BCLKDIV_64		0x02
>  #define ADAU1373_BCLKDIV_128		0x01
> @@ -937,7 +939,8 @@ static int adau1373_hw_params(struct snd_pcm_substream *substream,
>  	adau1373_dai->enable_src = (div != 0);
>  
>  	snd_soc_update_bits(codec, ADAU1373_BCLKDIV(dai->id),
> -		~ADAU1373_BCLKDIV_SOURCE, (div << 2) | ADAU1373_BCLKDIV_64);
> +		ADAU1373_BCLKDIV_SR_MASK | ADAU1373_BCLKDIV_BCLK_MASK,
> +		(div << 2) | ADAU1373_BCLKDIV_64);
>  
>  	switch (params_format(params)) {
>  	case SNDRV_PCM_FORMAT_S16_LE:

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