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[RFC,v2,0/2] ASoC: prepare streams on codec-to-codec links

Message ID 20250110210730.705613-1-martin.blumenstingl@googlemail.com (mailing list archive)
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Series ASoC: prepare streams on codec-to-codec links | expand

Message

Martin Blumenstingl Jan. 10, 2025, 9:07 p.m. UTC 
Hello,

the DRM subsystem has recently gained a HDMI audio codec framework [0].
This is already queued for Linux 6.14.

I want to implement a HDMI controller driver for the Amlogic
Meson8/8b/8m2 SoCs using the DRM HDMI audio codec framework. Internally
the DRM HDMI audio codec framework relies on hdmi-codec's .prepare
callback to be called. This unfortunately is not happening on Amlogic
Meson8/8b/8m2 platforms [1].

Jerome suggested that this may be because of the codec-to-codec link on
our Amlogic AIU audio driver [2]. He encouraged me to send this series
to allow hdmi-codec's .prepare() callback to be called - even on
platforms that connect it via a codec-to-codec link.

The reason why this series is marked as RFC is that I'm not familiar
with the ASoC subsystem and lot of the functionality and terminology
is new to me.

Also I Cc'ed Sylwester Nawrocki (Samsung maintainer) as codec-to-codec
links seem to be most heavily used on Samsung and Amlogic platforms.

Changes since v1 at [3]:
- updated patch #2 to also prepare the source side of the link for
  consistency reasons (as suggested by Jerome and Mark)


[0] https://lore.kernel.org/dri-devel/20241224-drm-bridge-hdmi-connector-v10-0-dc89577cd438@linaro.org/
[1] https://lore.kernel.org/linux-amlogic/CAFBinCDdiJ3UNVUcShjq=7U2=oUwT3ciYdKSuZ5TdcrikxFBpg@mail.gmail.com/
[2] https://lore.kernel.org/linux-amlogic/1ja5c4b4rt.fsf@starbuckisacylon.baylibre.com/
[3] https://lore.kernel.org/linux-sound/20250106141316.375984-1-martin.blumenstingl@googlemail.com/


Martin Blumenstingl (2):
  ASoC: soc-dai: add snd_soc_dai_prepare() and use it internally
  ASoC: dapm: add support for preparing streams

 include/sound/soc-dai.h |  3 +++
 sound/soc/soc-dai.c     | 27 +++++++++++++++++++--------
 sound/soc/soc-dapm.c    | 12 ++++++++++++
 3 files changed, 34 insertions(+), 8 deletions(-)