Re: [PATCH 1/2] dt-bindings: arm: arm,scmi: add smc/hvc transports

[Marc Zyngier]

On 2020-02-07 11:00, Peng Fan wrote:
> > Subject: Re: [PATCH 1/2] dt-bindings: arm: arm,scmi: add smc/hvc 
> > transports
> >
> > On 2020-02-07 10:47, Sudeep Holla wrote:
> > > On Fri, Feb 07, 2020 at 10:08:36AM +0000, Marc Zyngier wrote:
> > >> On 2020-02-06 13:01, peng.fan@xxxxxxx wrote:
> > >> > From: Peng Fan <peng.fan@xxxxxxx>
> > >> >
> > >> > SCMI could use SMC/HVC as tranports, so add into devicetree binding
> > >> > doc.
> > >> >
> > >> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > >> > ---
> > >> >  Documentation/devicetree/bindings/arm/arm,scmi.txt | 4 +++-
> > >> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >> >
> > >> > diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt
> > >> > b/Documentation/devicetree/bindings/arm/arm,scmi.txt
> > >> > index f493d69e6194..03cff8b55a93 100644
> > >> > --- a/Documentation/devicetree/bindings/arm/arm,scmi.txt
> > >> > +++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt
> > >> > @@ -14,7 +14,7 @@ Required properties:
> > >> >
> > >> >  The scmi node with the following properties shall be under the
> > >> > /firmware/ node.
> > >> >
> > >> > -- compatible : shall be "arm,scmi"
> > >> > +- compatible : shall be "arm,scmi" or "arm,scmi-smc"
> > >> >  - mboxes: List of phandle and mailbox channel specifiers. It
> > >> > should contain
> > >> >  	  exactly one or two mailboxes, one for transmitting messages("tx")
> > >> >  	  and another optional for receiving the notifications("rx") if
> > >> > @@ -25,6 +25,8 @@ The scmi node with the following properties shall
> > >> > be under the /firmware/ node.
> > >> >  	  protocol identifier for a given sub-node.
> > >> >  - #size-cells : should be '0' as 'reg' property doesn't have any size
> > >> >  	  associated with it.
> > >> > +- arm,smc-id : SMC id required when using smc transports
> > >> > +- arm,hvc-id : HVC id required when using hvc transports
> > >> >
> > >> >  Optional properties:
> > >>
> > >> Not directly related to DT: Why do we need to distinguish between SMC
> > >> and HVC?
> > >
> > > IIUC you want just one property to get the function ID ? Does that
> > > align with what you are saying ? I wanted to ask the same question and
> > > I see no need for 2 different properties.
> >
> > Exactly. Using SMC or HVC should come from the context, and there is 
> > zero
> > value in having different different IDs, depending on the conduit.
> >
> > We *really* want SMC and HVC to behave the same way. Any attempt to
> > make them different should just be NAKed.
>
> ok. Then just like psci node,
> Add a "method" property for each protocol, and add "arm,func-id" to
> indicate the ID.
>
> How about this?

Or rather just a function ID, full stop. the conduit *MUST* be inherited
from the PSCI context.

        M.
--
Jazz is not dead. It just smells funny...