Re: [PATCH v4] dt-bindings: arm: keystone: add boot_* mboxes to ti,sci

[Krzysztof Kozlowski <krzk@kernel.org>]

On Fri, Dec 05, 2025 at 11:45:43AM +0530, Anshul Dalal wrote:
> The bootloader on K3 devices makes use of mailboxes as per the ROM spec
> which might be different than one's available to the kernel (firmware
> spec).
> 
> Therefore, this patch adds the missing mailbox entries to the DT binding
> if the matching compatible is ti,am654-sci to represent the mailboxes
> exposed by the hardware during boot for the purpose of loading the
> firmware.
> 
> Signed-off-by: Anshul Dalal <anshuld@ti.com>
> ---
> Changes in v4:
> - Make new boot_* mboxes conditional on ti,am654-sci compatible
> - Link to v3: https://lore.kernel.org/r/20251112-k3_syscon_add_boot_mailboxes-v3-1-66155a4236dc@ti.com
> 
> Changes in v3:
> - Drop [1/2] of the last patch series
> - Update existing example with boot_* mailboxes instead of adding a new one
> - Link to v2: https://lore.kernel.org/r/20251112-k3_syscon_add_boot_mailboxes-v2-0-aebc1e47b391@ti.com
> 
> Changes in v2:
> - Remove maxItems entry
> - Remove RFC tag from patch (added by mistake in v1)
> - Document the new mailboxes in mboxes instead of mbox-names
> - Provide example with all the mailboxes set
> - Update commit title to have "ti,sci"
> - Split into two patches
> - Link to v1: https://lore.kernel.org/r/20251111-k3_syscon_add_boot_mailboxes-v1-1-529a27f21076@ti.com
> ---
>  .../devicetree/bindings/arm/keystone/ti,sci.yaml   | 50 +++++++++++++++++++---
>  1 file changed, 43 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
> index 25a2b42105e5..d9eb2a81e539 100644
> --- a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
> +++ b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
> @@ -51,15 +51,15 @@ properties:
>      minItems: 1
>  
>    mbox-names:
> +    minItems: 2
> +    maxItems: 6
>      description: |
>        Specifies the mailboxes used to communicate with TI-SCI Controller
>        made available from TI-SCI controller.
> -    items:
> -      - const: rx
> -      - const: tx
>  
>    mboxes:
>      minItems: 2
> +    maxItems: 6
>  
>    ti,host-id:
>      $ref: /schemas/types.yaml#/definitions/uint32
> @@ -79,6 +79,42 @@ properties:
>      type: object
>      $ref: /schemas/reset/ti,sci-reset.yaml#
>  
> +if:
> +  properties:
> +    compatible:
> +      contains:
> +        const: ti,am654-sci
> +then:
> +  properties:
> +    mbox-names:
> +      minItems: 2

Why is this list flexible?

> +      items:
> +        - const: rx
> +        - const: tx
> +        - const: notify
> +        - const: boot_rx
> +        - const: boot_tx
> +        - const: boot_notify

So this list goes to top-level with minItems.

> +    mboxes:
> +      minItems: 2
> +      items:
> +        - description: RX thread
> +        - description: TX thread
> +        - description: Notify thread
> +        - description: boot stage RX thread
> +        - description: boot stage TX thread
> +        - description: boot stage Notify thread

This as well

> +else:

Best regards,
Krzysztof