[PATCH V2] dt-bindings: mailbox: xlnx,zynqmp-ipi-mailbox: Document msg region requirement

[Jassi Brar]

On Fri, Jan 9, 2026 at 12:23 AM Harini T <harini.t at amd.com> wrote:
>
> Add description clarifying that for Versal IPI mailboxes, both host and
> remote agents must have the "msg" register region defined for successful
> message passing. Without both, only notification-based communication
> works.
>
> Signed-off-by: Harini T <harini.t at amd.com>
> ---
> Changes in V2:
> - The description regarding the "msg" register region requirement for Versal IPI
> mailboxes was moved from the conditional schema section to the main description
> block at the top of the YAML file.
>
> V1 link: https://lore.kernel.org/all/20251222044653.1757886-1-harini.t@amd.com/
> ---
>  .../bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml     | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
> index 04d6473d666f..a5205ee5ad0f 100644
> --- a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
> +++ b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
> @@ -11,6 +11,17 @@ description: |
>    messaging between two Xilinx Zynq UltraScale+ MPSoC IPI agents. Each IPI
>    agent owns registers used for notification and buffers for message.
>
> +  For Versal devices, there are two types of IPI channels:
> +    - Buffered channels: Support message passing and require the "msg"
> +    register region to be present on both the host and remote IPI agents.
> +    - Buffer-less channels: Support notification only and do not require the
> +    "msg" register region. For these channels, the "msg" region should be
> +    omitted.
> +
> +  For message passing, both the host and remote IPI agents must define the "msg"
> +  register region. If either agent omits the "msg" region, only notification
> +  based communication is possible.
> +
>                 +-------------------------------------+
>                 | Xilinx ZynqMP IPI Controller        |
>                 +-------------------------------------+
> --
> 2.43.0
>
Applied to mailbox/for-next.
Thanks.