Re: [PATCH v4 3/6] ASoC: dt-bindings: fsl_rpmsg: Add binding doc for rpmsg cpu dai driver

On Mon, Mar 08, 2021 at 09:22:27PM +0800, Shengjiu Wang wrote:

fsl_rpmsg cpu dai driver is driver for rpmsg audio, which is mainly used

Bindings describe h/w blocks, not drivers.

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 | 118 ++++++++++++++++++ 1 file changed, 118 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..5731c1fbc0a6 --- /dev/null +++ b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml @@ -0,0 +1,118 @@ +# 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

+description: |

• fsl_rpmsg cpu dai driver is virtual driver for rpmsg audio, which doesn't
• touch hardware. It 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.

+properties:

• compatible:
• enum:

•  - fsl,imx7ulp-rpmsg
  

•  - fsl,imx8mn-rpmsg
  

•  - fsl,imx8mm-rpmsg
  

•  - fsl,imx8mp-rpmsg
  

• model:
• $ref: /schemas/types.yaml#/definitions/string
• description: User specified audio sound card name
• 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

If this doesn't touch hardware, what are these clocks for?

You don't need 'minItems' unless it's less than the number of 'items'.

• 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
• enum: [0, 1]
• default: 0
• description: Instance index for sound card in

•             M core side, which share one rpmsg
  

•             channel.
  

We don't do indexes in DT. What's this numbering tied to?

• fsl,version:

version of what?

This seems odd at best.

• $ref: /schemas/types.yaml#/definitions/uint32
• enum: [1, 2]

You're going to update this with every new firmware version?

• default: 2
• description: The version of M core image, which is

•             to make driver compatible with different image.
  

• fsl,buffer-size:
• $ref: /schemas/types.yaml#/definitions/uint32
• description: pre allocate dma buffer size

How can you have DMA, this doesn't touch h/w?

• fsl,enable-lpa:
• $ref: /schemas/types.yaml#/definitions/flag
• description: enable low power audio path.
• fsl,rpmsg-out:
• $ref: /schemas/types.yaml#/definitions/flag
• description: |

•  This is a boolean property. If present, the transmitting function
  

•  will be enabled.
  

• fsl,rpmsg-in:
• $ref: /schemas/types.yaml#/definitions/flag
• description: |

•  This is a boolean property. If present, the receiving function
  

•  will be enabled.
  

• fsl,codec-type:
• $ref: /schemas/types.yaml#/definitions/uint32
• enum: [0, 1, 2]
• default: 0
• description: Sometimes the codec is registered by

•             driver not by the device tree, this items
  

•             can be used to distinguish codecs.
  

How does one decide what value to use?

• audio-codec:
• $ref: /schemas/types.yaml#/definitions/phandle
• description: The phandle of the audio codec

The codec is controlled from the Linux side?

• memory-region:
• $ref: /schemas/types.yaml#/definitions/phandle
• description: phandle to the reserved memory nodes

+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;
  

How does this work? Don't you need somewhere to put the 'rpmsg' data?

• };

-- 2.27.0