Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Krzysztof Kozlowski]

On 20/01/2024 12:20, Amrit Anand wrote:
> From: Elliot Berman <quic_eberman@xxxxxxxxxxx>
> 



> 
> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
> -------------------------------------------------------------
> The selection process for devicetrees was Qualcomm-specific and not
> useful for other devices and bootloaders that were not developed by
> Qualcomm because a complex algorithm was used to implement. Board-ids
> provide a matching solution that can be implemented by bootloaders
> without introducing vendor-specific code. Qualcomm uses three
> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
> pmic-id.  This does not scale well for use casese which use identifiers,
> for example, to distinguish between a display panel. For a display
> panel, an approach could be to add a new property: display-id,
> but now	bootloaders need to be updated to also read this property. We
> want to	avoid requiring to update bootloaders with new hardware

Some mis-indentation in two lines above.

> identifiers: a bootloader need only recognize the identifiers it can
> handle.
> 
> Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
> Signed-off-by: Amrit Anand <quic_amrianan@xxxxxxxxxxx>
> ---
>  .../devicetree/bindings/hwinfo/board-id.yaml       | 53 ++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwinfo/board-id.yaml b/Documentation/devicetree/bindings/hwinfo/board-id.yaml

I think we should add it to dtschema, because bootloaders are using these.

> new file mode 100644
> index 0000000..82d5ff7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
> @@ -0,0 +1,53 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Board Identifier for Devicetree Selection
> +
> +maintainers:
> +  - Amrit Anand <quic_amrianan@xxxxxxxxxxx>
> +  - Elliot Berman <quic_eberman@xxxxxxxxxxx>
> +
> +description: |

Do not need '|' unless you need to preserve formatting.

> +  Device manufacturers frequently ship multiple boards under a single
> +  software package. These software packages will ship multiple devicetree
> +  blobs and require some mechanism to pick the correct DTB for the board
> +  the software package was deployed. board-id provides a mechanism for
> +  bootloaders to select the appropriate DTB which is vendor/OEM-agnostic.
> +
> +select:
> +  anyOf:
> +    - required:
> +        - 'board-id'
> +    - required:
> +        - 'board-id-types'
> +    - required:
> +        - '#board-id-cells'

I don't fully get why do you need this select. Isn't the schema selected
by nodename? Or maybe it is for the final required: but then this could
be just set of dependencies.

> +
> +properties:
> +  $nodename:
> +    const: "/"

Blank line.

> +  board-id:
> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> +    description: |

Do not need '|' unless you need to preserve formatting.

> +      A list of identifiers that can be used to match with this devicetree.

s/devicetree/Devicetree/ ?

> +      The interpretatation of each cell can be matched with the

Typo: interpretation

> +      board-id-type at the same index.
> +
> +  board-id-types:
> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +    description:
> +      Defines the type of each cell, indicating to the DeviceTree selection

s/DeviceTree/Devicetree/ ?


> +      mechanism how to parse the board-id.
> +
> +  '#board-id-cells':

 What are the cells for?

> +    minimum: 1
> +
> +required:
> +  - board-id
> +  - board-id-types
> +  - '#board-id-cells'


> +
> +additionalProperties: true

Best regards,
Krzysztof