Hi Rob, Krzysztof, Mark,
On Thu, 4 May 2023 13:22:35 +0900 Mark Brown broonie@kernel.org wrote:
On Tue, May 02, 2023 at 09:26:32AM +0200, Krzysztof Kozlowski wrote:
On 26/04/2023 09:36, Herve Codina wrote:
Rob Herring robh@kernel.org wrote:
On Fri, Apr 21, 2023 at 02:41:19PM +0200, Herve Codina wrote:
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.
It means that often what people call "simple" and "generic" works only for their specific case, because it is not really simple and generic. After some time the "simple" and "generic" becomes "complicated" and "huge". Conclusion: sometimes simple and generic bindings are bad idea and you should have something specific.
Your description in the binding also does not help to match it to specific, real device. Provide the examples, as Rob asked.
I don't understand what you are looking for here. IIO is a subsystem which represents generic DACs and ADCs (along with other I/O things). Audio devices also have DACs and ADCs, somewhat specialised for use in audio but more limited by specs and interfaces than by anything fundamental. The goal here is to map DACs and ADCs described as IIO for use in an audio context.
ADCs are devices that convert analog signals into digital values, DACs are devices that convert digital values into analog signals.
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:
Just like Rob said: "You'd need a link to each 'aux' node"
and you did it...
So now the rest of Rob's answer:
"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."
Why do you need another node if it is not really representing a real, separate device?
If nothing else I would expect it to be useful from a comprehensibility point of view to bundle multiple IIO devices into a single multi-channel audio stream, an individual IIO device is likely to only present a single channel of data but it is common to group multiple channels of audio data.
I cannot simply add io-channels to the sound card directly. I need a node to set at least the sound-name-prefix property. Further more having a node and a related compatible string can be easier to maintain and add future evolution related to these "virtual" devices.
As some subnodes are already defined for a sound card node, I propose to group these "virtual" audio devices node in a specific bundle node. This lead to the following example: ---- 8< ---- 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"; };
};
sound { compatible = "simple-audio-card"; #address-cells = <1>; #size-cells = <0>; simple-audio-card,name = "My Sound Card";
simple-audio-card,aux-devs = <&_in>, <&_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 { ... };
...
/* A bundle for the additional devices */ simple-audio-card,additional-devs { amp_out: aux-out { compatible = "audio-iio-aux"; /* Instead of "simple-iio-aux */ io-channels = <&pot_out 0>, <&pot_out 1>, io-channel-names = "CH0", "CH1"; snd-control-invert-range = <1 1>; /* Old 'invert' renamed */ sound-name-prefix = "AMP_OUT"; };
amp_in: aux-in { compatible = "audio-iio-aux"; io-channels = <&pot_in 0>, <&pot_in 1>; io-channel-names = "CH0", "CH1"; sound-name-prefix = "AMP_IN"; }; }; }; ---- 8< ----
What do you think about this new binding ?
Best regards, Hervé