[alsa-devel] [PATCH] ASoC: davinci-mcasp: Choose PCM driver based on configured DMA controller

[Peter Ujfalusi]

On 06/02/2015 11:58 AM, Jyri Sarha wrote:
> Find the configured DMA controller by asking for a DMA channel in the
> probe phase and releasing it right after. The controller device can be
> found via the dma_chan struct and the controller is recognized from
> the compatible property of its device node. The patch assumes EDMA if
> there is no device node.
> 
> Signed-off-by: Jyri Sarha <jsarha at ti.com>
> ---
>  sound/soc/davinci/davinci-mcasp.c | 61 ++++++++++++++++++++++++++++++++-------
>  1 file changed, 51 insertions(+), 10 deletions(-)
> 
> diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
> index d793494..5bc2712 100644
> --- a/sound/soc/davinci/davinci-mcasp.c
> +++ b/sound/soc/davinci/davinci-mcasp.c
> @@ -1565,6 +1565,46 @@ static int davinci_mcasp_init_ch_constraints(struct davinci_mcasp *mcasp)
>  	return ret;
>  }
>  
> +enum {
> +	MCASP_EDMA = 1,

Why start from 1?
I'm not sure about the name. It somehow implies that McASP has something to do
with the dma engine.
MCASP_SERVICED_BY_E/SDMA
PLATFORM_USES_E/SDMA

I can not come up with a decent name :(


> +	MCASP_SDMA,
> +};
> +static const char *sdma_prefix = "ti,omap";
> +
> +static int davinci_mcasp_get_dma_type(struct davinci_mcasp *mcasp)
> +{
> +	struct dma_chan *chan;
> +	const char *tmp;
> +	int ret = MCASP_EDMA;
> +
> +	tmp = mcasp->dma_data[SNDRV_PCM_STREAM_PLAYBACK].filter_data;
> +	chan = dma_request_slave_channel_reason(mcasp->dev, tmp);

this will return with error in case of !dev->of_node.
The first check should be:
if (!mcasp->dev->of_node)
	return MCASP_EDMA;

since we can only boot in legacy mode with daVinci devices and they are using
eDMA.

> +	if (IS_ERR(chan)) {
> +		if (PTR_ERR(chan) != -EPROBE_DEFER)
> +			dev_err(mcasp->dev,
> +				"Can't verify DMA configuration (%ld)\n",
> +				PTR_ERR(chan));
> +		return PTR_ERR(chan);
> +	}
> +	BUG_ON(!chan->device || !chan->device->dev);
> +
> +	if (chan->device->dev->of_node)
> +		ret = of_property_read_string(chan->device->dev->of_node,
> +					      "compatible", &tmp);
> +	else
> +		dev_dbg(mcasp->dev, "DMA controller has no of-node\n");

Now this is not likely to happen...

> +
> +	dma_release_channel(chan);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(mcasp->dev, "DMA controller compatible = \"%s\"\n", tmp);
> +	if (!strncmp(tmp, sdma_prefix, strlen(sdma_prefix)))
> +		return MCASP_SDMA;
> +
> +	return MCASP_EDMA;
> +}
> +
>  static int davinci_mcasp_probe(struct platform_device *pdev)
>  {
>  	struct snd_dmaengine_dai_dma_data *dma_data;
> @@ -1763,27 +1803,28 @@ static int davinci_mcasp_probe(struct platform_device *pdev)
>  	if (ret != 0)
>  		goto err;
>  
> -	switch (mcasp->version) {
> +	ret = -EINVAL;

Why? What was the problem with setting the ret in the default case?

> +	switch (davinci_mcasp_get_dma_type(mcasp)) {
> +	case MCASP_EDMA:
>  #if IS_BUILTIN(CONFIG_SND_EDMA_SOC) || \
>  	(IS_MODULE(CONFIG_SND_DAVINCI_SOC_MCASP) && \
>  	 IS_MODULE(CONFIG_SND_EDMA_SOC))
> -	case MCASP_VERSION_1:
> -	case MCASP_VERSION_2:
> -	case MCASP_VERSION_3:
>  		ret = edma_pcm_platform_register(&pdev->dev);
> -		break;
> +#else
> +		dev_err(&pdev->dev, "Missing SND_EDMA_SOC\n");
>  #endif
> +		break;
> +	case MCASP_SDMA:
>  #if IS_BUILTIN(CONFIG_SND_OMAP_SOC) || \
>  	(IS_MODULE(CONFIG_SND_DAVINCI_SOC_MCASP) && \
>  	 IS_MODULE(CONFIG_SND_OMAP_SOC))
> -	case MCASP_VERSION_4:
>  		ret = omap_pcm_platform_register(&pdev->dev);
> -		break;
> +#else
> +		dev_err(&pdev->dev, "Missing SND_SDMA_SOC\n");
>  #endif
> +		break;
>  	default:
> -		dev_err(&pdev->dev, "Invalid McASP version: %d\n",
> -			mcasp->version);
> -		ret = -EINVAL;
> +		dev_err(&pdev->dev, "No DMA controller found\n");
>  		break;
>  	}
>  
> 


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