linux-kernel - Re: [PATCH RFC v2 4/6] arm64: dts: qcom: sm8450-hdk: Enable I2S for HDMI

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Message-ID: <d8e202fb-f494-4b5e-bfb9-c94c1fd3af4d@linaro.org>
Date: Thu, 9 Oct 2025 14:52:56 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 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>
Cc: linux-sound@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH RFC v2 4/6] arm64: dts: qcom: sm8450-hdk: Enable I2S for
 HDMI

On 10/9/25 14:37, Konrad Dybcio wrote:
> On 10/8/25 8:56 PM, 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/sm8450-hdk.dts | 26 +++++++++++++++++++++
>>   arch/arm64/boot/dts/qcom/sm8450.dtsi    | 40 +++++++++++++++++++++++++++++++++
>>   2 files changed, 66 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sm8450-hdk.dts b/arch/arm64/boot/dts/qcom/sm8450-hdk.dts
>> index 0c6aa7ddf43263f30595b3f0733ec3e126e38608..7b822086a57c600ae9b5668d6d7a375d0ec55fa7 100644
>> --- a/arch/arm64/boot/dts/qcom/sm8450-hdk.dts
>> +++ b/arch/arm64/boot/dts/qcom/sm8450-hdk.dts
>> @@ -667,6 +667,8 @@ lt9611_codec: hdmi-bridge@2b {
>>   		pinctrl-names = "default";
>>   		pinctrl-0 = <&lt9611_irq_pin &lt9611_rst_pin>;
>>   
>> +		#sound-dai-cells = <1>;
>> +
>>   		ports {
>>   			#address-cells = <1>;
>>   			#size-cells = <0>;
>> @@ -1016,6 +1018,14 @@ &sound {
>>   			"TX SWR_INPUT0", "ADC3_OUTPUT",
>>   			"TX SWR_INPUT1", "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 = "primart-mi2s",
> 
> "primary-mi2s"
> 
> [...]

Damn typo

> 
>> +			audio_mclk0_default_state: audio-mclk0-default-state {
>> +				pins = "gpio125";
>> +				function = "pri_mi2s";
>> +				drive-strength = <8>;
>> +				bias-disable;
>> +				output-high;
>> +			};
>> +
>> +			i2s0_default_state: i2s0-default-state {
>> +				sck-pins {
>> +					pins = "gpio126";
>> +					function = "mi2s0_sck";
>> +					drive-strength = <8>;
>> +					bias-disable;
>> +					output-high;
> 
> I doubt output-high for a clock pin is what you want..

This was copied from downstream:

================><============================
		i2s0_sck_active: i2s0_sck_active {
<snip>
			config {
				pins = "gpio126";
				drive-strength = <8>;   /* 8 mA */
				bias-disable;           /* NO PULL */
				output-high;
			};
<snip>
		i2s0_ws_active: i2s0_ws_active {
<snip>
			config {
				pins = "gpio129";
				drive-strength = <8>;   /* 8 mA */
				bias-disable;           /* NO PULL */
				output-high;
			};
================><============================

And also set the same way arch/arm64/boot/dts/qcom/sm4250.dtsi

And I guess this level would only set when the function is not active.

Neil

> 
>> +				};
>> +
>> +				data0-pins {
>> +					pins = "gpio127";
>> +					function = "mi2s0_data0";
>> +					drive-strength = <8>;
>> +					bias-disable;
>> +				};
>> +
>> +				data1-pins {
>> +					pins = "gpio128";
>> +					function = "mi2s0_data1";
>> +					drive-strength = <8>;
>> +					bias-disable;
>> +				};
>> +
>> +				ws-pins {
>> +					pins = "gpio129";
>> +					function = "mi2s0_ws";
>> +					drive-strength = <8>;
>> +					bias-disable;
>> +					output-high;
> 
> here too
> 
> Konrad