ROC-RK3588S-PC Bluetooth SCO no sound when device is used as a HFP headset/louds

moiommo

Hello,

I want to use my ROC-RK3588S-PC device as a handsfree headset that is connected to a mobile phone. I managed to get a dialer app work, so it can receive and send callls using Android services. The only issue left that I cannot resolve is a missing sound via SCO. I beleive that there is no sound as Bluetoth SCO is not registered as a sound card which makes impossible to route audio. Wireless chip RTL8821CU has pins for SCO that exposes PCM signals and can be used as an audio device.



I tried to build a custom image to sovle that issue with Device Tree patched.

I modified 'kernel-5.10/arch/arm64/boot/dts/rockchip/roc-rk3588s-pc.dtsi'

1. / {
   
2. ...
   
3. /*Bluetooth SCO sound card */
   
4. 
   
5.   bt-sound {
   
6.      compatible = "simple-audio-card";
   
7.      simple-audio-card,format = "dsp_a";
   
8.      simple-audio-card,bitclock-inversion = <1>;
   
9.      simple-audio-card,mclk-fs = <256>;
   
10.      simple-audio-card,name = "rockchip,bt";
    
11.      simple-audio-card,cpu {
    
12.      // sound-dai = <&i2s2_2ch>;
    
13.      sound-dai = <&i2s3_2ch>;
    
14.     };
    
15. 
    
16.     simple-audio-card,codec {
    
17.       sound-dai = <&bt_sco>;
    
18.    };
    
19.   };
    
20. 
    
21.    bt_sco: bt-sco {
    
22.     compatible = "delta,dfbmcs320";
    
23.     #sound-dai-cells = <0>;
    
24.     status = "okay";
    
25.   };
    
26. }
    

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Then I tried to use i2s2_2ch and i2s3_2ch pin adress foond in 'kernel-5.10/arch/arm64/boot/dts/rockchip/rk3588s.dtsi', unfortunatly both variants didn't work as pins are  already taken by other devices.

1. &i2s2_2ch{
   
2.   pinctrl-0 = <&i2s2m1_lrck
   
3.   &i2s2m1_sclk
   
4.   &i2s2m1_sdi
   
5.   &i2s2m1_sdo>;
   
6.   status = "okay";
   
7. };
   

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dmesg output for &i2s2_2ch:

1. [    5.348697] [    T1] usbcore: registered new interface driver snd-usb-audio
   
2. [    5.351654] [    T1] rockchip-pinctrl pinctrl: pin gpio3-13 already requested by fe1c0000.ethernet; cannot claim for fe490000.i2s
   
3. [    5.351665] [    T1] rockchip-pinctrl pinctrl: pin-109 (fe490000.i2s) status -22
   
4. [    5.351672] [    T1] rockchip-pinctrl pinctrl: could not request pin 109 (gpio3-13) from group i2s2m1-sclk  on device rockchip-pinctrl
   
5. [    5.351678] [    T1] rockchip-i2s fe490000.i2s: Error applying setting, reverse things back
   
6. [    5.351691] [    T1] rockchip-i2s: probe of fe490000.i2s failed with error -22

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&i2s3_2ch{
  pinctrl-0 = <&i2s3_lrck
  &i2s3_sclk
  &i2s3_sdi
  &i2s3_sdo>;
  status = "okay";
};

dmesg output for &i2s3_2ch:

[    5.349054] [    T1] usbcore: registered new interface driver snd-usb-audio
[    5.351490] [    T1] rockchip-pinctrl pinctrl: pin gpio3-2 already requested by fe1c0000.ethernet; cannot claim for fe4a0000.i2s
[    5.351498] [    T1] rockchip-pinctrl pinctrl: pin-98 (fe4a0000.i2s) status -22
[    5.351503] [    T1] rockchip-pinctrl pinctrl: could not request pin 98 (gpio3-2) from group i2s3-lrck  on device rockchip-pinctrl
[    5.351508] [    T1] rockchip-i2s fe4a0000.i2s: Error applying setting, reverse things back
[    5.351519] [    T1] rockchip-i2s: probe of fe4a0000.i2s failed with error -22

Could someone privide right configuration for Blutooth SCO PCM output pins of RTL8821CU for  ROC-RK3588S-PC device or suggest anothe way to sove issue with missing sound.


Best regards