Re: [PATCH v2] ASoC: dt-bindings: simple-card: add triggers properties

19 Jul 2023


      On 19.07.2023 01:08, Rob Herring wrote:
...
On Sat, Jul 15, 2023 at 11:30:43AM +0300, Maxim Kochetkov wrote:
...
The trigger-start/stop properties allows to specify DAI link
trigger ordering method.
Obviously. Why do you need these? What problem does it solve?
It allows using simple card for some DMA-based CPU component which 
requires different start/stop sequence (stop DMA before CPU component, 
start DMA after CPU component).
There are a lot of boards which have no audio codec on board. It has 
only I2S/TDM/etc... and you can attach any external codec on its pins. 
It looks like simple audio card is enough for this cases. It is much 
better than to copy-paste simple audio card code to the new custom 
driver with new combination of CPU/codec.
...
I don't think these belong in simple-card. What's next? What if you need
delays between each step? This is the problem with 'simple' or 'generic'
bindings. It's a never ending addition of properties which are not well
thought out.
Can you please suggest the better way to specify start/stop trigger 
order via DT?
...
...

trigger-start:
description: |-
 Start trigger ordering method:


 default: Link->Component->DAI


 ldc: Link->DAI->Component


$ref: /schemas/types.yaml#/definitions/string
items:
 enum:


   - default



Why do you need a value of 'default'? What's the default when the
property is not present?
It comes from
enum snd_soc_trigger_order {
    SND_SOC_TRIGGER_ORDER_DEFAULT	= 0,	
    SND_SOC_TRIGGER_ORDER_LDC,		
    SND_SOC_TRIGGER_ORDER_MAX,
};
default value is 0 (SND_SOC_TRIGGER_ORDER_DEFAULT)
...
...
format:
  description: audio format.
  items:

@@ -210,6 +232,10 @@ properties:
      maxItems: 1
    simple-audio-card,mic-det-gpio:
      maxItems: 1

simple-audio-card,trigger-start:
$ref: "#/definitions/trigger-start"
simple-audio-card,trigger-stop:
$ref: "#/definitions/trigger-stop"

Don't continue this 'simple-audio-card,' prefix pattern. With it, no
other binding can use these properties.
Ok.
...
...
patternProperties:
    "^simple-audio-card,cpu(@[0-9a-f]+)?$":
@@ -259,6 +285,11 @@ patternProperties:
          maxItems: 1
        mic-det-gpio:
          maxItems: 1

 trigger-start:


   $ref: "#/definitions/trigger-start"


 trigger-stop:


   $ref: "#/definitions/trigger-stop"




Should I keep only this section?

    