On Fri Apr 25, 2025 at 11:06 PM CEST, Konrad Dybcio wrote:
> On 4/25/25 12:44 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 interrupts should
>> appear on the xhci-hcd interrupts during playback, instead the ADSP will
>> be handling the playback.
>
> "should" isn't very optimistic - I assume this works for you? >
Yes it does!
With 'should' I meant to describe the expected behavior from using this
since most people are probably not familiar with how this works.
>> Signed-off-by: Luca Weiss <luca.we...@fairphone.com>
>> ---
> [...]
>
>> +&sound {
>> + compatible = "fairphone,fp4-sndcard";
>> + model = "Fairphone 4";
>> +
>> + mm1-dai-link {
>> + link-name = "MultiMedia1";
>> +
>> + cpu {
>> + sound-dai = <&q6asmdai MSM_FRONTEND_DAI_MULTIMEDIA1>;
>> + };
>> + };
>> +
>> + usb-dai-link {
>> + link-name = "USB Playback";
>> +
>> + cpu {
>> + sound-dai = <&q6afedai USB_RX>;
>> + };
>> +
>> + codec {
>> + sound-dai = <&q6usbdai USB_RX>;
>> + };
>
> 'co'dec < 'cp'u> +
Aah, I thought I checked for that already. Will fix.
>> + platform {
>> + sound-dai = <&q6routing>;
>> + };
>> + };
>> +};
>> +
>> &tlmm {
>> gpio-reserved-ranges = <13 4>, <56 2>;
>>
>> @@ -1178,6 +1214,7 @@ &usb_1 {
>> &usb_1_dwc3 {
>> maximum-speed = "super-speed";
>> dr_mode = "otg";
>> + num-hc-interrupters = /bits/ 16 <3>;
> Where does this number come from?
I'm honestly not 100% sure. As far as I understand it, with
'qcom,usb-audio-intr-idx = /bits/ 16 <2>;' in the qcom,q6usb node (which
I've checked against downstream) we declare which "XHCI interrupter
number to use". Without the num-hc-interrupters property we get an error
that not enough interrupters are available (I assume only 1 is then), so
this value practically needs to be higher than the <2> from earlier.
Why it's this value and not a higher value e.g. 4 I'm not really sure.
Downstream code looks somewhat different and "max_interrupters" in
drivers/usb/ doesn't come from a dt property. I'd need to check more in
details what this code does - or maybe Wesley can help.
Regards
Luca
>
> Konrad
