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SubjectRE: [EXT] Re: [PATCH v2 1/7] ASoC: dt-bindings: fsl_rpmsg: Add a property to assign the rpmsg channel
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> >>> Add a string property to assign the rpmsg channel this sound card sits
> >>> on. It also represents the name of ASoC platform driver. This property
> >>> can be omitted if there is only one sound card and it sits on
> >>> "rpmsg-audio-channel".
> >>>
> >>> Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
> >>> ---
> >>> .../devicetree/bindings/sound/fsl,rpmsg.yaml | 37
> ++++++++++++++++++-
> >>> 1 file changed, 35 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> >> b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> >>> index d370c98a62c7..3744ae794c00 100644
> >>> --- a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> >>> +++ b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> >>> @@ -11,8 +11,11 @@ maintainers:
> >>>
> >>> description: |
> >>> fsl_rpmsg is a virtual audio device. Mapping to real hardware devices
> >>> - are SAI, DMA controlled by Cortex M core. What we see from Linux
> >>> - side is a device which provides audio service by rpmsg channel.
> >>> + are SAI, MICFIL, DMA controlled by Cortex M core. What we see from
> >>> + Linux side is a device which provides audio service by rpmsg channel.
> >>> + We can create different sound cards which access different hardwares
> >>> + such as SAI, MICFIL, .etc through building rpmsg channels between
> >>> + Cortex-A and Cortex-M.
> >>>
> >>> properties:
> >>> compatible:
> >>> @@ -85,6 +88,17 @@ properties:
> >>> This is a boolean property. If present, the receiving function
> >>> will be enabled.
> >>>
> >>> + fsl,rpmsg-channel-name:
> >>> + $ref: /schemas/types.yaml#/definitions/string
> >>> + description: |
> >>> + A string property to assign rpmsg channel this sound card sits on.
> >>> + It also represents the name of ASoC platform driver. This property
> >>
> >> That's a Linux detail which doesn't belong in DT.
> >>
> >
> > We pass hardware parameters in dts node to set up clocks or other
> > configurations. These configurations are finally sent to Cortex-M by
> > rpmsg channel because Cortex-M actually controls real hardware devices.
> > If there's only one sound card sits on one rpmsg channel we will not
> > need this property. But if there are several sound cards we need to
> > specify correct rpmsg channel. Thus hardware configurations can be
> > properly sent to Cortex-M. From this level to speak, this property is
> > hardware-related since rpmsg channel represents the real hardware audio
> > controller.
> >
> > Here I attach the discussion in version 1 patches for your information:
> > ---
> > This property aims to tell the ASoC driver which rpmsg channel the
> > sound card depends on. If there are several sound cards sit on rpmsg,
> > we should pass correct information in dts node to specify the name of
> > rpmsg channel. That is why I meant to add this property.
> >
> > Actually this property is hardware-related. As we discussed before,
> > this kind of sound card based on rpmsg works under this mechanism
> > Cortex-A core tells the Cortex-M core configuration of the PCM
> > parameters then Cortex-M controls real hardware devices. This property
> > specifying rpmsg channel represents the real hardware audio controller.
> > ---
> >
> > That's my idea adding this property. Do you have any suggstion?
>
> I think you misunderstood the comment. Rob's comment was directly below
> a line which he referred to. That line contained a statement referring
> to Linux drivers. Anything related to Linux drivers does not belong to DT.
>
>
> Best regards,
> Krzysztof

Thanks for explaining the meaning and giving more details. I will
delete the statement referring to linux drivers. Indeed this property
is designed to assign the rpmsg channel name.
Does it look better if I modify the code like this:

+ fsl,rpmsg-channel-name:
+ $ref: /schemas/types.yaml#/definitions/string
+ description: |
+ A string property to assign rpmsg channel this sound card sits on.
+ This property can be omitted if there is only one sound card and it sits
+ on "rpmsg-audio-channel".
+ enum:
+ - rpmsg-audio-channel
+ - rpmsg-micfil-channel

Regards,
Chancel Liu
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