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

[Marc Zyngier]

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.

Thanks,

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