From your output of zgrep ROCKCHIP /proc/config.gz, we can see that Rockchip audio support (CONFIG_SND_SOC_ROCKCHIP=y) is enabled, but there is no mention of CONFIG_SND_SOC_HDMI_CODEC=m or CONFIG_SND_HDA_CODEC_HDMI, which could indicate that HDMI audio support (required for audio passthrough) might ...