Re: [PATCH v8 03/10] arm_ffa: introduce Arm FF-A low-level driver

Sudeep Holla
2023-01-20T10:33:47Z

On Thu, Jan 19, 2023 at 12:11:34PM -0600, Rob Herring wrote:
> On Thu, Jan 19, 2023 at 10:41 AM Simon Glass <sjg@chromium.org> wrote:
> >
> > Can you add a DT node for the 'FF-A SW interfaces' and attach some
> > sort of top-level driver to that? Perhaps simple-bus, or your own
> > thing? You don't need to add compatible strings for subnodes (devices
> > that are discoverable within that).
>
> We already have that. It's just called 'arm,psci'. FF-A is not the
> top-level thing. SMCCC is. That's unfortunately called PSCI in DT
> because SMCCC grew out of PSCI. Evolution is ugly...
>
> It's like this:
>
> SMCCC
> +--PSCI
> +--TRNG
> +--FF-A
> +--SCMI (sometimes)
> +--OP-TEE
> +--...Whatever Arm comes up with next...
>

Thanks Rob for the nice description.

Hi Simon,

Though SMCCC and PSCI are kind of swapped in reality like Rob mentioned
while referring to the ugly evolution, we are trying to stick with PSCI
node and discovery other features dynamically in the kernel. Hope the
reasons for not defining the extra unnecessary bindings for FF-A is clear
now.

There are couple of other bindings IIRC, one being for the OPTEE for example
which again could have been avoid if we had better idea on how these SMCCC and
its users would have evolved.

--
Regards,
Sudeep