Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

From: Sudeep Holla

Date: Fri Jan 30 2026 - 07:35:58 EST



+Cristian(in case I am talking no sense)

On Fri, Jan 30, 2026 at 11:31:25AM +0100, Andre Przywara wrote:
>
> So do you need just one "tx", but "rx" plus "rx_reply"? Which isn't valid in
> the current binding?
> If that's the case, then we would need a patch to relax the binding and
> allowing this combination as well.
> Looking into the kernel code it looks like the SCMI driver doesn't use
> mbox-names, but explicitly expects assignments depending on the number of
> mboxes? Somewhat confusing ...
>

It is generally transmitted via tx, and tx_reply is necessary when the
platform has unidirectional channels. tx_reply is used to determine when the
synchronization commands have completed, without requiring polling of the
shared memory. rx_reply is necessary only if the platform firmware expects
it and doesn't poll the shared memory for OSPM/agent acknowledgement.

--
Regards,
Sudeep