Re: [PATCH 1/4] dt-bindings: sound: Add simple-iio-aux

Hi Rob,

On Tue, 25 Apr 2023 12:30:29 -0500 Rob Herring robh@kernel.org wrote:

On Fri, Apr 21, 2023 at 02:41:19PM +0200, Herve Codina wrote:

...

Industrial I/O devices can be present in the audio path. These devices needs to be viewed as audio components in order to be fully integrated in the audio path.

simple-iio-aux allows to consider these Industrial I/O devices as auxliary audio devices.

What makes it simple? Any binding called simple or generic is a trigger for me. Best to avoid those terms. :)

I choose simple-iio-aux because some simple-* already exists. For instance simple-audio-amplifier or simple-audio-mux.

Do you prefer audio-iio-aux ? Let me know if I should change.

Examples of devices would be useful here.

...

Signed-off-by: Herve Codina herve.codina@bootlin.com

.../bindings/sound/simple-iio-aux.yaml | 65 +++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/devicetree/bindings/sound/simple-iio-aux.yaml

diff --git a/Documentation/devicetree/bindings/sound/simple-iio-aux.yaml b/Documentation/devicetree/bindings/sound/simple-iio-aux.yaml new file mode 100644 index 000000000000..fab128fce4fc --- /dev/null +++ b/Documentation/devicetree/bindings/sound/simple-iio-aux.yaml @@ -0,0 +1,65 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/sound/simple-iio-aux.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml#

+title: Simple IIO auxiliary

+maintainers:

• • Herve Codina herve.codina@bootlin.com

+description: |

Don't need '|'

Will be fixed.

...

• Auxiliary device based on Industrial I/O device channels

+allOf:

• • $ref: /schemas/iio/iio-consumer.yaml

You don't need to reference consumer schemas.

Right, will be removed.

...

• • $ref: dai-common.yaml#

+properties:

• compatible:
• const: simple-iio-aux
• io-channels:
• description:

•  Industrial I/O device channels used
  

• io-channel-names:
• description:

•  Industrial I/O channel names related to io-channels.
  

•  These names are used to provides sound controls, widgets and routes names.
  

• invert:

Property names should globally only have 1 type definition. This is generic enough I'd be concerned that's not the case.

What do you mean ?

...

• $ref: /schemas/types.yaml#/definitions/uint32-array
• description: |

•  A list of 0/1 flags defining whether or not the related channel is
  

•  inverted
  

• items:

•  enum: [0, 1]
  

•  default: 0
  

•  description: |
  

•    Invert the sound control value compared to the IIO channel raw value.
  

•      - 1: The related sound control value is inverted meaning that the
  

•           minimum sound control value correspond to the maximum IIO channel
  

•           raw value and the maximum sound control value correspond to the
  

•           minimum IIO channel raw value.
  

•      - 0: The related sound control value is not inverted meaning that the
  

•           minimum (resp maximum) sound control value correspond to the
  

•           minimum (resp maximum) IIO channel raw value.
  

+required:

• • compatible
• • io-channels
• • io-channel-names

+unevaluatedProperties: false

+examples:

• • |
• aux {

•    compatible = "simple-iio-aux";
  

•    io-channels = <&iio 0>, <&iio 1>, <&iio 2>, <&iio 3>;
  

•    io-channel-names = "CH0", "CH1", "CH2", "CH3";  
  

Not really useful names. Do you have a real example?

As Mark said, for IIO channel, using CHx makes sense. See below, I provide a full example.

...

•    /* Invert CH1 and CH2 */
  

•    invert = <0 1 1>;  
  

IMO, invert should be same length as io-channels.

I will update.

Related to this topic, when I wrote this binding, I wanted to add some rules/constraints in order to: - Have this property optional - If present, force to have as many items in the invert array as the number of items present in the io-channels array.

I never succeed in writing the constraint for the invert property. It should be possible (it is done for some 'foo' 'foo-names' pair such as clocks). Can you tell me if possible in my case and give me some pointers ?

...

• };

How do support multiple instances? Say you have 2 sound cards (or 1 sound card with multiple audio paths) each with different sets of IIO channels associated with it. You'd need a link to each 'aux' node. Why not just add io-channels to the sound card nodes directly? That's already just a virtual, top-level container node grouping all the components. I don't see why we need another virtual node grouping a subset of them.

I don't see what you mean. I use a simple-audio-card and here is a full example using several instances:

spi { #address-cells = <1>; #size-cells = <0>; /* potentiometers present in an input amplifier design */ pot_in: potentiometer@0 { compatible = "foo,xxx"; reg = <0>; #io-channel-cells = <1>; }; /* potentiometers present in an output amplifier design */ pot_out: potentiometer@1 { compatible = "foo,xxx"; reg = <1>; #io-channel-cells = <1>; }; /* A codec */ codec: codec@2 { compatible = "bar,yyy"; reg = <2>; sound-name-prefix = "CODEC"; };

};

amp_out: aux-out { compatible = "simple-iio-aux"; io-channels = <&pot_out 0>, <&pot_out 1>, io-channel-names = "CH0", "CH1"; invert = <1 1>; sound-name-prefix = "AMP_OUT"; };

amp_in: aux-in { compatible = "simple-iio-aux"; io-channels = <&pot_in 0>, <&pot_in 1>; io-channel-names = "CH0", "CH1"; sound-name-prefix = "AMP_IN"; };

sound { compatible = "simple-audio-card"; #address-cells = <1>; #size-cells = <0>; simple-audio-card,name = "My Sound Card";

simple-audio-card,aux-devs = <&amp_in>, <&amp_out>; simple-audio-card,routing = "CODEC IN0", "AMP_IN CH0 OUT", "CODEC IN1", "AMP_IN CH1 OUT", "AMP_OUT CH0 IN", "CODEC OUT0", "AMP_OUT CH1 IN", "CODEC OUT1",

simple-audio-card,dai-link@0 { ... }; };

Best regards, Hervé