Hello there,
https://community.nxp.com/t5/i-MX-Processors/Can-iMX7ULP-or-iMX8-act-as-USB-Audio-Class-2-0-device/t...
according to the link above, I apply the patch on linux-4.19.35 to fix the yellow mark in Win10 Device Manager and successfully drive i.mx6ull as a usb soundcard, both capture and playback are OK. But I do the same thing on linux-4.1.15, executing aplay on i.mx6ull is working well, but executing arecord will report error:
arecord: pcm_read:2096: read error: Input/output error.
seems no audio data is captured, I'm not sure which part I'm missing.
I couldn't use linux-4.19.35 directlly because the kernel will be stuck when I access to some memory area, such as execute readl or insmod kernel module, it seems some memory area is protected by certain function, I disable the OPTEE and the problem is still exist.
hope someone can help me, thanks a lot.
