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

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

[Harini T]

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@amd.com>
---
 .../bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml           | 6 ++++++
 1 file changed, 6 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..8fdf77c7935c 100644
--- a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
+++ b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
@@ -165,6 +165,12 @@ allOf:
         reg-names: false
 
     else:
+      description:
+        For Versal IPI mailboxes, the "msg" register region is optional.
+        However, for successful message passing via mailbox, both the host IPI
+        agent and the remote IPI agent must have the "msg" register region
+        defined. If either agent lacks the "msg" field, only notification-based
+        communication (without message buffers) will work.
       properties:
         reg:
           items:
-- 
2.43.0

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

[Krzysztof Kozlowski]

On Mon, Dec 22, 2025 at 10:16:53AM +0530, Harini T 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@amd.com>
> ---
>  .../bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml           | 6 ++++++
>  1 file changed, 6 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..8fdf77c7935c 100644
> --- a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
> +++ b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml
> @@ -165,6 +165,12 @@ allOf:
>          reg-names: false
>  
>      else:
> +      description:

Else block cannot have description.

> +        For Versal IPI mailboxes, the "msg" register region is optional.

So it is optional...

> +        However, for successful message passing via mailbox, both the host IPI

And it is not optional. If nothing works, then it is not optional.

And why would it be optional in the first place? You generate your same
IP with different settings?

Best regards,
Krzysztof

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

[T, Harini]

[Public]

Hi,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzk@kernel.org>
> Sent: Monday, December 22, 2025 2:39 PM
> To: T, Harini <Harini.T@amd.com>
> Cc: jassisinghbrar@gmail.com; robh@kernel.org; krzk+dt@kernel.org;
> conor+dt@kernel.org; Simek, Michal <michal.simek@amd.com>; Datta,
> Shubhrajyoti <shubhrajyoti.datta@amd.com>; linux-kernel@vger.kernel.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; git (AMD-
> Xilinx) <git@amd.com>
> Subject: Re: [PATCH] dt-bindings: mailbox: xlnx,zynqmp-ipi-mailbox:
> Document msg region requirement
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Mon, Dec 22, 2025 at 10:16:53AM +0530, Harini T 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@amd.com>
> > ---
> >  .../bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml           | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.ya
> > ml
> > b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.ya
> > ml index 04d6473d666f..8fdf77c7935c 100644
> > ---
> > a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.ya
> > ml
> > +++ b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbo
> > +++ x.yaml
> > @@ -165,6 +165,12 @@ allOf:
> >          reg-names: false
> >
> >      else:
> > +      description:
>
> Else block cannot have description.

Can I remove the description from else block and move the clarifying text to the top-level description field?

>
> > +        For Versal IPI mailboxes, the "msg" register region is optional.
>
> So it is optional...

The schema marks "msg" as optional to support both notification-only and message-passing use-cases. In hardware, some mailbox channels may be designed for notification only (no buffer), while others support full message passing (with buffer). The schema allows both, but for message passing, "msg" is required on both ends

>
> > +        However, for successful message passing via mailbox, both the
> > + host IPI
>
> And it is not optional. If nothing works, then it is not optional.
>
> And why would it be optional in the first place? You generate your same IP
> with different settings?

There are 2 types of IPI channels (Buffered and Buffer-less)
Some IPI channels are used only for notification (no message buffer, so "msg" is omitted).
Others are used for message passing (buffer present, so "msg" is required).
Reference: https://docs.amd.com/r/en-US/am026-versal-ai-edge-prime-gen2-trm/Features?tocId=K2dUHSdNOkFPpbvkR5v6bQ

>
> Best regards,
> Krzysztof

Thanks,
Harini T

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

[Krzysztof Kozlowski]

On 23/12/2025 11:48, T, Harini wrote:
> [Public]

What? Fix your email client, so we wan't be dealing with your corporate
rules.

[Private]

or rather let's mess with corporate systems:

[Confidential]

> 
> Hi,
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzk@kernel.org>
>> Sent: Monday, December 22, 2025 2:39 PM
>> To: T, Harini <Harini.T@amd.com>
>> Cc: jassisinghbrar@gmail.com; robh@kernel.org; krzk+dt@kernel.org;
>> conor+dt@kernel.org; Simek, Michal <michal.simek@amd.com>; Datta,
>> Shubhrajyoti <shubhrajyoti.datta@amd.com>; linux-kernel@vger.kernel.org;
>> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; git (AMD-
>> Xilinx) <git@amd.com>
>> Subject: Re: [PATCH] dt-bindings: mailbox: xlnx,zynqmp-ipi-mailbox:
>> Document msg region requirement
>>
>> Caution: This message originated from an External Source. Use proper caution
>> when opening attachments, clicking links, or responding.
>>
>>
>> On Mon, Dec 22, 2025 at 10:16:53AM +0530, Harini T 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@amd.com>
>>> ---
>>>  .../bindings/mailbox/xlnx,zynqmp-ipi-mailbox.yaml           | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.ya
>>> ml
>>> b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.ya
>>> ml index 04d6473d666f..8fdf77c7935c 100644
>>> ---
>>> a/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbox.ya
>>> ml
>>> +++ b/Documentation/devicetree/bindings/mailbox/xlnx,zynqmp-ipi-mailbo
>>> +++ x.yaml
>>> @@ -165,6 +165,12 @@ allOf:
>>>          reg-names: false
>>>
>>>      else:
>>> +      description:
>>
>> Else block cannot have description.
> 
> Can I remove the description from else block and move the clarifying text to the top-level description field?
> 
>>
>>> +        For Versal IPI mailboxes, the "msg" register region is optional.
>>
>> So it is optional...
> 
> The schema marks "msg" as optional to support both notification-only and message-passing use-cases. In hardware, some mailbox channels may be designed for notification only (no buffer), while others support full message passing (with buffer). The schema allows both, but for message passing, "msg" is required on both ends

This is not wrapped. Again, fix your email client.

> 
>>
>>> +        However, for successful message passing via mailbox, both the
>>> + host IPI
>>
>> And it is not optional. If nothing works, then it is not optional.
>>
>> And why would it be optional in the first place? You generate your same IP
>> with different settings?
> 
> There are 2 types of IPI channels (Buffered and Buffer-less)
> Some IPI channels are used only for notification (no message buffer, so "msg" is omitted).


Confusing description then.

> 


Best regards,
Krzysztof