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

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Message-ID: <30f0f5ef-a148-444f-924f-594f4cbd48a4@linux.intel.com>
Date:   Fri, 3 Nov 2023 10:39:42 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        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




> 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.

The configuration seems fine, but the problem is the
"sdw_stream_runtime" definition.

You need *ONE* sdw_stream_runtime, and multiple m_rt contexts added in
the linked lists of this sdw_stream_runtime. In other words, you need to
call sdw_stream_add_master() twice, for swr0 and swr3 respectively.

Put differently, a sdw_stream_runtime does not point to a specific bus,
it provides a top-level structure which can use multiple buses.

The best way to allocate the sdw_stream_runtime is to rely on the
dailink .startup callback. From the description above that's where you
have all the needed information, and then each DAI .startup (or
hw_params) can call sdw_stream_add_master() to update the linked lists.