Re: [PATCH v2 3/7] ASoC: dt-bindings: fsl_rpmsg: Add binding doc for rpmsg cpu dai driver

[Shengjiu Wang <shengjiu.wang@gmail.com>]

On Thu, Feb 11, 2021 at 6:13 AM Rob Herring <robh@kernel.org> wrote:
>
> On Sun, Feb 07, 2021 at 06:23:51PM +0800, Shengjiu Wang wrote:
> > fsl_rpmsg cpu dai driver is driver for rpmsg audio, which is mainly used
> > for getting the user's configuration from device tree and configure the
> > clocks which is used by Cortex-M core. So in this document define the
> > needed property.
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > ---
> >  .../devicetree/bindings/sound/fsl,rpmsg.yaml  | 80 +++++++++++++++++++
> >  1 file changed, 80 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> > new file mode 100644
> > index 000000000000..2d3ce10d42fc
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
> > @@ -0,0 +1,80 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/sound/fsl,rpmsg.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: NXP Audio RPMSG CPU DAI Controller
> > +
> > +maintainers:
> > +  - Shengjiu Wang <shengjiu.wang@nxp.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - fsl,imx7ulp-rpmsg
> > +      - fsl,imx8mn-rpmsg
> > +      - fsl,imx8mm-rpmsg
> > +      - fsl,imx8mp-rpmsg
>
> rpmsg is a protocol. What's the h/w block?

On Linux side this driver is a virtual driver, it is running
on Arm Cortex-A core. The h/w block is controlled by
another core (cortex-M core). so this driver actually
doesn't touch any hardware, it just does configuration
for rpmsg channel.

>
> > +
> > +  clocks:
> > +    items:
> > +      - description: Peripheral clock for register access
> > +      - description: Master clock
> > +      - description: DMA clock for DMA register access
> > +      - description: Parent clock for multiple of 8kHz sample rates
> > +      - description: Parent clock for multiple of 11kHz sample rates
> > +    minItems: 5
> > +
> > +  clock-names:
> > +    items:
> > +      - const: ipg
> > +      - const: mclk
> > +      - const: dma
> > +      - const: pll8k
> > +      - const: pll11k
> > +    minItems: 5
> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +  fsl,audioindex:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: instance index for rpmsg image
> > +
> > +  fsl,version:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: rpmsg image version index
>
> What are these 2 used for?

fsl,audioindex: As we may support multiple instance, for example
two sound card with one rpmsg channel, this is the instance index.

fsl,version: There are maybe different image running on M core, this
is the image version, different image has different function.


>
> > +
> > +  fsl,buffer-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: pre allocate dma buffer size
> > +
> > +  fsl,enable-lpa:
> > +    $ref: /schemas/types.yaml#/definitions/flag
> > +    description: enable low power audio path.
> > +
> > +  fsl,codec-type:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: Sometimes the codec is registered by
> > +                 driver not the device tree, this items
> > +                 can be used to distinguish codecs
>
> 0-2^32 are valid values?

I should add range for it.

>
> > +
> > +required:
> > +  - compatible
> > +  - fsl,audioindex
> > +  - fsl,version
> > +  - fsl,buffer-size
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    rpmsg_audio: rpmsg_audio {
> > +        compatible = "fsl,imx8mn-rpmsg";
> > +        fsl,audioindex = <0> ;
> > +        fsl,version = <2>;
> > +        fsl,buffer-size = <0x6000000>;
> > +        fsl,enable-lpa;
> > +        status = "okay";
>
> Don't show status in examples.

ok, will remove it.

>
> > +    };
> > --
> > 2.27.0
> >