linux-kernel - Re: [PATCH RFC 4/6] sm8650-hdk: Enable I2S for HDMI

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Message-Id: <DDC7B1BDTZCN.D7JXN4RVKYHM@linaro.org>
Date: Tue, 07 Oct 2025 16:39:01 +0100
From: "Alexey Klimov" <alexey.klimov@...aro.org>
To: "Neil Armstrong" <neil.armstrong@...aro.org>
Cc: "Srinivas Kandagatla" <srini@...nel.org>, "Liam Girdwood"
 <lgirdwood@...il.com>, "Mark Brown" <broonie@...nel.org>, "Jaroslav Kysela"
 <perex@...ex.cz>, "Takashi Iwai" <tiwai@...e.com>, "Rob Herring"
 <robh@...nel.org>, "Krzysztof Kozlowski" <krzk+dt@...nel.org>, "Conor
 Dooley" <conor+dt@...nel.org>, "Bjorn Andersson" <andersson@...nel.org>,
 "Konrad Dybcio" <konradybcio@...nel.org>, <linux-sound@...r.kernel.org>,
 <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <devicetree@...r.kernel.org>
Subject: Re: [PATCH RFC 4/6] sm8650-hdk: Enable I2S for HDMI

On Tue Oct 7, 2025 at 8:04 AM BST, Neil Armstrong wrote:
> On 10/7/25 03:39, Alexey Klimov wrote:
>> On Mon Oct 6, 2025 at 7:37 PM BST, Neil Armstrong wrote:
>>> Add the necessary nodes to configure the right I2S interface
>>> to output audio via the DSI HDMI bridge.
>>>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>>> ---
>>>   arch/arm64/boot/dts/qcom/sm8650-hdk.dts | 30 +++++++++++++++++++++++++
>>>   arch/arm64/boot/dts/qcom/sm8650.dtsi    | 40 +++++++++++++++++++++++++++++++++
>>>   2 files changed, 70 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sm8650-hdk.dts b/arch/arm64/boot/dts/qcom/sm8650-hdk.dts
>>> index 87d7190dc991b11f5d1162aabb693dcadd198c51..1286ce95235d5544322a1877292cbdd426298c11 100644
>>> --- a/arch/arm64/boot/dts/qcom/sm8650-hdk.dts
>>> +++ b/arch/arm64/boot/dts/qcom/sm8650-hdk.dts
>>> @@ -171,6 +171,19 @@ sound {
>>>   				"TX SWR_INPUT1", "ADC2_OUTPUT",
>>>   				"TX SWR_INPUT3", "ADC4_OUTPUT";
>>>   
>>> +		pinctrl-0 = <&i2s0_default_state>, <&audio_mclk0_default_state>;
>>> +		pinctrl-names = "default";
>>> +
>>> +		clocks = <&q6prmcc LPASS_CLK_ID_PRI_MI2S_IBIT LPASS_CLK_ATTRIBUTE_COUPLE_NO>,
>>> +			 <&q6prmcc LPASS_CLK_ID_MCLK_1 LPASS_CLK_ATTRIBUTE_COUPLE_NO>;
>>> +		clock-names = "pri-mi2s",
>>> +			      "pri-mclk";
>>> +
>>> +		assigned-clocks = <&q6prmcc LPASS_CLK_ID_PRI_MI2S_IBIT LPASS_CLK_ATTRIBUTE_COUPLE_NO>,
>>> +				  <&q6prmcc LPASS_CLK_ID_MCLK_1 LPASS_CLK_ATTRIBUTE_COUPLE_NO>;
>>> +		assigned-clock-rates = <1536000>,
>>> +				       <24576000>;
>>> +
>>>   		wcd-playback-dai-link {
>>>   			link-name = "WCD Playback";
>>>   
>>> @@ -218,6 +231,22 @@ platform {
>>>   				sound-dai = <&q6apm>;
>>>   			};
>>>   		};
>>> +
>>> +		pri-mi2s-dai-link {
>>> +			link-name = "Primary MI2S Playback";
>> 
>> Is it HDMI only audio playback or does it have switches to playback it as raw i2s
>> (when external DAC is needed)?
>
> The HDK has i2s lines of the secondary i2s on the LS connector, but without any additional
> boards connected it has no on-board i2s dacs.

Ah, like on RB3 and RB5 boards.

In such case the suggestion is to add mention of HDMI here in the link name,
otherwise it might be not clear what this multi i2s playback is about.
Maybe "Primary MI2S/HDMI Playback" will do.

Thanks,
Alexey