imx8mp SPDIF TX does not produce a lockable signal

[Fabio Estevam]

On Fri, Dec 12, 2025 at 4:11 PM Fabio Estevam <festevam at gmail.com> wrote:

> Any suggestions for debugging or fixing this would be appreciated.

The SPDIF TX audio locks and operation now works.

The key thing was to pass AES1 information.

In /etc/asound.conf:

pcm.spdif_out {
    type iec958
    slave {
        format IEC958_SUBFRAME_LE
        pcm {
            type hw
            card imxaudioxcvr
        }
    }
    status [ 0x00 0x0A 0x00 0x00 ]
    preamble.z 0x0
    preamble.x 0x1
    preamble.y 0x3
}

Play the wav file:
aplay -D plug:spdif_out  96-24.wav

or a 440 Hz tone via speaker test:

speaker-test -D plug:spdif_out -c 2 -t sine

Thanks