linux-kernel - Re: [PATCH 2/2] arm64: dts: qcom: qcm6490-fairphone-fp5: Enable USB audio offload support

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Message-Id: <DBR5EH6T22S3.O4U97PRZF1BI@fairphone.com>
Date: Fri, 01 Aug 2025 16:07:31 +0200
From: "Luca Weiss" <luca.weiss@...rphone.com>
To: "Konrad Dybcio" <konrad.dybcio@....qualcomm.com>,
 <cros-qcom-dts-watchers@...omium.org>, "Bjorn Andersson"
 <andersson@...nel.org>, "Konrad Dybcio" <konradybcio@...nel.org>, "Rob
 Herring" <robh@...nel.org>, "Krzysztof Kozlowski" <krzk+dt@...nel.org>,
 "Conor Dooley" <conor+dt@...nel.org>, "Wesley Cheng"
 <quic_wcheng@...cinc.com>, "Stephan Gerhold" <stephan.gerhold@...aro.org>
Cc: <~postmarketos/upstreaming@...ts.sr.ht>, <phone-devel@...r.kernel.org>,
 <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] arm64: dts: qcom: qcm6490-fairphone-fp5: Enable USB
 audio offload support

On Fri Aug 1, 2025 at 4:03 PM CEST, Konrad Dybcio wrote:
> On 8/1/25 3:51 PM, Luca Weiss wrote:
>> Enable USB audio offloading which allows to play audio via a USB-C
>> headset with lower power consumption and enabling some other features.
>> 
>> This can be used like the following:
>> 
>>   $ amixer -c0 cset name='USB_RX Audio Mixer MultiMedia1' On
>>   $ aplay --device=plughw:0,0 test.wav
>> 
>> Compared to regular playback to the USB sound card no xhci-hcd
>> interrupts appear during playback, instead the ADSP will be handling the
>> USB transfers.
>> 
>> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
>> ---
>>  arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>> 
>> diff --git a/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts b/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts
>> index e115b6a52b299ef663ccfb614785f8f89091f39d..d30912f952db271aa4fbc2570ca04b771ffef3ca 100644
>> --- a/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts
>> +++ b/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts
>> @@ -1176,6 +1176,22 @@ platform {
>>  			sound-dai = <&q6routing>;
>>  		};
>>  	};
>> +
>> +	usb-dai-link {
>> +		link-name = "USB Playback";
>> +
>> +		codec {
>> +			sound-dai = <&q6usbdai USB_RX>;
>> +		};
>> +
>> +		cpu {
>> +			sound-dai = <&q6afedai USB_RX>;
>> +		};
>> +
>> +		platform {
>> +			sound-dai = <&q6routing>;
>> +		};
>
> Because this is SoC component <-> SoC component mapping, this could live
> in the SoC dtsi.. but then 7280 is a glorious mess with the firmware
> flavors, so I suppose it should stay here..

q6afe definitely doesn't exist on the RB3Gen2 for example with
AudioReach, so yeah... I guess also the sound setup on other (simpler)
platforms can be simplified quite a bit, but it's (unfortunately) not
yet a major concern given the limited number of boards with good and
complete audio support.

>
> Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>

Thanks!

Regards
Luca

>
> Konrad