linux-kernel - Re: [PATCH 1/2] ASoC: qcom: Add helper for allocating Soundwire stream runtime

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Date:   Wed, 29 Nov 2023 17:35:28 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Vinod Koul <vkoul@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Banajit Goswami <bgoswami@...cinc.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-arm-msm@...r.kernel.org,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        linux-sound@...r.kernel.org
Subject: Re: [PATCH 1/2] ASoC: qcom: Add helper for allocating Soundwire
 stream runtime

On 28/11/2023 18:39, Pierre-Louis Bossart wrote:
> 
>> +int qcom_snd_sdw_startup(struct snd_pcm_substream *substream)
>> +{
>> +	struct snd_soc_pcm_runtime *rtd = substream->private_data;
>> +	struct snd_soc_dai *cpu_dai = snd_soc_rtd_to_cpu(rtd, 0);
>> +	struct sdw_stream_runtime *sruntime;
>> +	struct snd_soc_dai *codec_dai;
>> +	int ret, i;
>> +
>> +	sruntime = sdw_alloc_stream(cpu_dai->name);
>> +	if (!sruntime)
>> +		return -ENOMEM;
>> +
>> +	for_each_rtd_codec_dais(rtd, i, codec_dai) {
>> +		ret = snd_soc_dai_set_stream(codec_dai, sruntime,
>> +					     substream->stream);
>> +		if (ret < 0 && ret != -ENOTSUPP) {
> 
> I know this is existing code moved into a helper, but out of curiosity
> why is -ENOTSUPP ignored? Isn't this problematic?

This is for all DAI links, so if some don't have set_stream callback, we
assume it is not needed. For example few codecs do not need it because
they are not on Soundwire bus at all and they don't care about the stream.

> 
>> +			dev_err(rtd->dev, "Failed to set sdw stream on %s\n",
>> +				codec_dai->name);
>> +			goto err_set_stream;
>> +		}
>> +	}
> 
> Also should the CPU DAIs also be used to set the stream information?
> it's not clear to me why only the CODEC DAIs are used.

I don't know, we never did. As you pointed out, I am just moving things
around, so I don't really know the original intention.


Best regards,
Krzysztof