linux-kernel - [PATCH V3 0/2] ASoC: audio_graph_card2: Support variable slot widths

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Message-ID: <20220228172754.453783-1-rf@opensource.cirrus.com>
Date:   Mon, 28 Feb 2022 17:27:52 +0000
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <broonie@...nel.org>, <robh+dt@...nel.org>,
        <kuninori.morimoto.gx@...esas.com>
CC:     <alsa-devel@...a-project.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH V3 0/2] ASoC: audio_graph_card2: Support variable slot widths

This adds support for I2S/TDM links where the slot width varies
depending on the sample width, in a way that cannot be guessed by
component hw_params().

A typical example is:

- 16-bit samples use 16-bit slots
- 24-bit samples use 32-bit slots

There is no way for a component hw_params() to deduce from the information
it is passed that 24-bit samples will be in 32-bit slots.

Some audio hardware cannot support a fixed slot width or a slot width
equal to the sample width in all cases. This is usually due either to
limitations of the audio serial port or system clocking restrictions.

These two patches add support for defining a mapping between sample widths
and sample slots. This allows audio_graph_card2 to be used in these
situations instead of having to write a custom machine driver.

Changes since V2:
- Change property type to uint32-matrix.
- Put min/max ranges on cells.
- Use per-item description to document the tuple entries.
- Add a slot count to the tuple - it's unlikely that this would change
  for different sample rates but it's trivial to implement support for it.
- Minor tidying of the code in asoc_simple_parse_tdm_width_map() and
  asoc_simple_set_tdm().

Richard Fitzgerald (2):
  ASoC: dt-bindings: audio-graph-port: Add dai-tdm-slot-width-map
  ASoC: audio_graph_card2: Add support for variable slot widths

 .../bindings/sound/audio-graph-port.yaml      | 20 ++++
 include/sound/simple_card_utils.h             | 11 +++
 sound/soc/generic/audio-graph-card2.c         |  4 +
 sound/soc/generic/simple-card-utils.c         | 97 +++++++++++++++++++
 4 files changed, 132 insertions(+)

-- 
2.30.2