linux-kernel - Re: [PATCH v4 6/8] dt-bindings: Add support for Amlogic GXBB SCPI Interface

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Date:   Wed, 2 Nov 2016 22:51:02 -0500
From:   Rob Herring <robh@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Olof Johansson <olof@...om.net>,
        Neil Armstrong <narmstrong@...libre.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-amlogic@...ts.infradead.org,
        Kevin Hilman <khilman@...libre.com>,
        Heiko Stübner <heiko@...ech.de>,
        Caesar Wang <wxt@...k-chips.com>,
        Frank Wang <frank.wang@...k-chips.com>
Subject: Re: [PATCH v4 6/8] dt-bindings: Add support for Amlogic GXBB SCPI Interface

On Wed, Nov 2, 2016 at 5:20 PM, Sudeep Holla <sudeep.holla@....com> wrote:
> On Sat, Oct 29, 2016 at 11:39:05AM -0700, Olof Johansson wrote:
>> Hi,
>>
>>
>> On Wed, Oct 5, 2016 at 12:33 AM, Neil Armstrong <narmstrong@...libre.com> wrote:
>> > Acked-by: Rob Herring <robh@...nel.org>
>> > Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> > ---
>> >  Documentation/devicetree/bindings/arm/arm,scpi.txt | 8 +++++---
>> >  1 file changed, 5 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/Documentation/devicetree/bindings/arm/arm,scpi.txt b/Documentation/devicetree/bindings/arm/arm,scpi.txt
>> > index faa4b44..04bc171 100644
>> > --- a/Documentation/devicetree/bindings/arm/arm,scpi.txt
>> > +++ b/Documentation/devicetree/bindings/arm/arm,scpi.txt
>> > @@ -7,7 +7,7 @@ by Linux to initiate various system control and power operations.
>> >
>> >  Required properties:
>> >
>> > -- compatible : should be "arm,scpi"
>> > +- compatible : should be "arm,scpi" or "amlogic,meson-gxbb-scpi"
>>
>> This doesn't seem right to document here. If anything you might want
>> to have a table of more-specific-compatibles for specific
>> implementations, but "arm,scpi" should still be the compatible of the
>> node (just not the most specific one).
>>
>
> I completely agree with you and I was pushing for a generic "arm,legacy-scpi"
> compatible until this binding was acked by Rob.

Just because I ack something, that doesn't mean don't review or
comment on it further.

>
> Anyways, I will add the generic compatible and post the changes.
>
>> Also, documenting it here indiciates that non-amlogic implementations
>> can/should use that compatible, which is misleading.
>>
>
> Agreed, it's better to keep them out of this generic binding document.
>
>> >  - mboxes: List of phandle and mailbox channel specifiers
>> >           All the channels reserved by remote SCP firmware for use by
>> >           SCPI message protocol should be specified in any order
>> > @@ -60,7 +60,8 @@ A small area of SRAM is reserved for SCPI communication between application
>> >  processors and SCP.
>> >
>> >  Required properties:
>> > -- compatible : should be "arm,juno-sram-ns" for Non-secure SRAM on Juno
>> > +- compatible : should be "arm,juno-sram-ns" for Non-secure SRAM on Juno,
>> > +               or "amlogic,meson-gxbb-sram" for Amlogic GXBB SoC.
>>
>> Maybe you'd be better of with a meson-specific document that refers to
>> these but with different compatible values.
>>
>> Come to think of it, the Juno-specific one maybe shouldn't be in
>> arm,scpi at all, since that adds confusion here.
>>
>> It's somewhat confusing that ARM is both a platform, architecture and
>> in some cases implementer of specific systems. :)
>>
>
> Sorry for that, I will move all juno specific references in the binding
> out of this document(except the examples, which I assume should be fine)
>
>> >  The rest of the properties should follow the generic mmio-sram description
>> >  found in ../../sram/sram.txt
>> > @@ -70,7 +71,8 @@ Each sub-node represents the reserved area for SCPI.
>> >  Required sub-node properties:
>> >  - reg : The base offset and size of the reserved area with the SRAM
>> >  - compatible : should be "arm,juno-scp-shmem" for Non-secure SRAM based
>> > -              shared memory on Juno platforms
>> > +              shared memory on Juno platforms or
>> > +              "amlogic,meson-gxbb-scp-shmem" for Amlogic GXBB SoC.
>>
>> Same here. It won't scale if all vendors are expected to add an entry here.
>>
>
> I will rework the patches to address the concerns as I too did share same
> concern.

Guess I was optimistic that *every* platform wouldn't be different in
some way. I should know better by now...

Rob