imx8mp SPDIF TX does not produce a lockable signal

[Shengjiu Wang]

On Sat, Dec 13, 2025 at 6:12 AM Fabio Estevam <festevam at gmail.com> wrote:
>
> 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.

Yes,  the only supported format is IEC958 in driver,  so need to convert to this
format from alsa-lib.

Best regards
Shengjiu Wang
>
> 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