linux-kernel - Re: [PATCH 13/15] ASoC: SND_S3C_DMA_LEGACY needs S3C24XX

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Date:	Fri, 2 May 2014 10:24:52 -0700
From:	Mark Brown <broonie@...nel.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Xia Kaixu <kaixu.xia@...aro.org>, linux-kernel@...r.kernel.org,
	linaro-kernel@...ts.linaro.org,
	Liam Girdwood <lgirdwood@...il.com>,
	Ben Dooks <ben-linux@...ff.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Sangbeom Kim <sbkim73@...sung.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH 13/15] ASoC: SND_S3C_DMA_LEGACY needs S3C24XX_DMA

On Fri, May 02, 2014 at 12:35:21AM +0200, Arnd Bergmann wrote:
> On Thursday 01 May 2014 12:11:25 Mark Brown wrote:

> > Why is the fix for this not to ensure that s3c24xx always enables the
> > DMA controller - how likely is it that it would be sane to build a
> > kernel without DMA after all?

> S3C24XX_DMA is only needed for ASoC and for s3cmci. The latter
> uses 'depends on S3C24XX_DMA'. arch/arm/configs/tct_hammer_defconfig
> is an example of a configuration that does not include DMA because
> it uses neither of the two drivers.

I'm having a hard time caring about that, the arch code can always do an
"if whatever".  If that board is what I think it actually does have
audio on it, either the defconfig was never updated or the driver wasn't
merged into mainline.

> How about the patch below?

I guess (modulo the issues below).  Killing the wrapper and making the
existing selection of DMA support actually select DMA support does avoid
the redundancy.

> diff --git a/sound/soc/samsung/ac97.c b/sound/soc/samsung/ac97.c
> index 76b072b..28fe097 100644
> --- a/sound/soc/samsung/ac97.c
> +++ b/sound/soc/samsung/ac97.c
> @@ -253,10 +253,7 @@ static int s3c_ac97_trigger(struct snd_pcm_substream *substream, int cmd,
>  
>  	writel(ac_glbctrl, s3c_ac97.regs + S3C_AC97_GLBCTRL);
>  
> -	if (!dma_data->ops)
> -		dma_data->ops = samsung_dma_get_ops();
> -
> -	dma_data->ops->started(dma_data->channel);
> +	s3c2410_dma_ctrl(dma_data->channel, S3C2410_DMAOP_STARTED);
>  
>  	return 0;
>  }

This code is broken in general - at least s3c64xx has AC'97.  That's
broken anyway though.

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