Re: [RFC v2 2/2] ASoC: dapm: add support for preparing streams

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Fri, Jan 10, 2025 at 10:07:30PM +0100, Martin Blumenstingl wrote:
> Codec driver can implement .hw_params and/or .prepare from struct
> snd_soc_dai_ops. For codec-to-codec links only the former (.hw_params)
> callback has been called.
> 
> On platforms like Amlogic Meson8/8b/8m2 the SoC's sound card
> (sound/soc/meson/gx-card.c) uses a codec-to-codec link for the HDMI
> codec output because further digital routing is required after the
> backend. The new DRM HDMI (audio) codec framework (which internally
> uses sound/soc/codecs/hdmi-codec.c) relies on the .prepare callback
> of the hdmi-codec to be called. Implement calls to
> snd_soc_dai_prepare() so the .prepare callback is called. In this
> case the mandatory part is the call to prepare the sink (which is
> the hdmi-codec on those platforms). Also call snd_soc_dai_prepare()
> for the source to stay consistent with the rest of the code (even
> though it's not strictly necessary to make the DRM HDMI codec
> framework work on Amlogic Meson8/8b/8m2).
> 
> For platforms or sound cards without a codec-to-codec link with
> additional parameters (which applies to most hardware) this changes
> nothing as the .prepare callback is already called via
> snd_pcm_do_prepare() (as well as dpcm_fe_dai_prepare() and
> dpcm_be_dai_prepare()) on those.
> 
> Suggested-by: Jerome Brunet <jbrunet@baylibre.com>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---

Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>

Thanks,
Charles