On Thu, Dec 17, 2020 at 04:08:12PM +0100, Jerome Brunet wrote:
> When the axg-tdm-interface was introduced, the backend DAI was marked as an
> endpoint when DPCM was walking the DAPM graph to find a its BE.
>
> It is no longer the case since this
> commit 8dd26dff00c0 ("ASoC: dapm: Fix handling of custom_stop_condition on DAPM graph walks")
> Because of this, when DPCM finds a BE it does everything it needs on the
> DAIs but it won't power up the widgets between the FE and the BE if there
> is no actual endpoint after the BE.
>
> On meson-axg HWs, the loopback is a special DAI of the tdm-interface BE.
> It is only linked to the dummy codec since there no actual HW after it.
> >From the DAPM perspective, the DAI has no endpoint. Because of this, the TDM
> decoder, which is a widget between the FE and BE is not powered up.
>
> >From the user perspective, everything seems fine but no data is produced.
>
> Connecting the Loopback DAI to a dummy DAPM endpoint solves the problem.
>
> Fixes: 8dd26dff00c0 ("ASoC: dapm: Fix handling of custom_stop_condition on DAPM graph walks")
> Cc: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
> ---
Reviewed-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>
Thanks,
Charles
