linux-kernel - Re: [PATCH 3/3] ASoC: codecs: wsa884x: check if set

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Date:   Fri, 3 Nov 2023 15:16:30 +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
Subject: Re: [PATCH 3/3] ASoC: codecs: wsa884x: check if set_stream is called
 for proper bus

On 25/10/2023 17:03, Pierre-Louis Bossart wrote:
> 
> 
> On 10/25/23 09:46, Krzysztof Kozlowski wrote:
>> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>
>> If multiple WSA8840 speakers, from two separate Soundwire buses, are
>> used in one codec DAI link, the set_stream() should ignore calls for
>> setting stream from other Soundwire controller.
>>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>> Co-developed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> ---
>>  sound/soc/codecs/wsa884x.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/sound/soc/codecs/wsa884x.c b/sound/soc/codecs/wsa884x.c
>> index bee6e763c700..91205e8c96f1 100644
>> --- a/sound/soc/codecs/wsa884x.c
>> +++ b/sound/soc/codecs/wsa884x.c
>> @@ -1775,6 +1775,12 @@ static int wsa884x_set_stream(struct snd_soc_dai *dai,
>>  			      void *stream, int direction)
>>  {
>>  	struct wsa884x_priv *wsa884x = dev_get_drvdata(dai->dev);
>> +	struct sdw_stream_runtime *sruntime = stream;
>> +	struct sdw_slave *sdw = dev_to_sdw_dev(dai->dev);
>> +
>> +	/* Check if this belongs to same bus */
>> +	if (sdw->bus->dev != sruntime->dev)
>> +		return 0;
> 
> Sorry, maybe I am really thick or need coffee, but I can't figure out
> why this is necessary. Each amplifier has its own "wsa884x_priv" context
> and should have its own DAI, not following why the set_stream would
> mix-up the two dais?
> 
> We've been using two buses for two amplifiers since CometLake (2019?)
> and I don't see what's different?

Let me start with some hardware representation in DTS.

We have two Soundwire controllers swr0 and swr3, each with two WSA884x
speakers (codecs):

-------------
&swr0 {
	status = "okay";

	left_woofer: speaker@0,0 {
		compatible = "sdw20217020400";
		reg = <0 0>;
		// ...
	};

	/* WSA8845, Left Tweeter */
	left_tweeter: speaker@0,1 {
		compatible = "sdw20217020400";
		reg = <0 1>;
		// ...
	};
};

&swr3 {
	status = "okay";

	/* WSA8845, Right Woofer */
	right_woofer: speaker@0,0 {
		compatible = "sdw20217020400";
		reg = <0 0>;
		// ...
	};

	/* WSA8845, Right Tweeter */
	right_tweeter: speaker@0,1 {
		compatible = "sdw20217020400";
		reg = <0 1>;
		// ...
	};
};
-------------

Now, for four-speaker playback, we have sound card with links like:

-------------
wsa-dai-link {
	link-name = "WSA Playback";

	cpu {
		sound-dai = <&q6apmbedai WSA_CODEC_DMA_RX_0>;
	};

	codec {
		sound-dai = <&left_woofer>, <&left_tweeter>,
			    <&swr0 0>, <&lpass_wsamacro 0>,
			    <&right_woofer>, <&right_tweeter>,
			    <&swr3 0>, <&lpass_wsa2macro 0>;
	};

	platform {
		sound-dai = <&q6apm>;
	};
};
-------------

We need to prepare the stream for all four speakers and two soundwire
controllers (so two different soundwire buses), however without the
patches here, the stream (sdw_stream_runtime *sruntime) right
woofer/twitter is set to swr0 (the other bus!). But it should stay as
swr3 (their bus).

Does it help a bit? I hope I am able to properly explain it.

Thanks for your feedback and review!

Best regards,
Krzysztof