Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936542AbcKKHsi (ORCPT ); Fri, 11 Nov 2016 02:48:38 -0500 Received: from foss.arm.com ([217.140.101.70]:36368 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932934AbcKKHsg (ORCPT ); Fri, 11 Nov 2016 02:48:36 -0500 Subject: Re: [PATCH v5 6/8] Documentation: bindings: add compatible specific to legacy SCPI protocol To: Olof Johansson References: <1478148731-11712-1-git-send-email-sudeep.holla@arm.com> <1478148731-11712-7-git-send-email-sudeep.holla@arm.com> <20161110012249.ed56ik6kdffoikym@rob-hp-laptop> <14e563ae-36c5-4bf9-0d51-3b07830de3db@arm.com> <7ccc12bc-9a05-47e3-8ab8-d1b0ad31159e@arm.com> Cc: Sudeep Holla , Rob Herring , Neil Armstrong , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , linux-amlogic@lists.infradead.org From: Sudeep Holla Message-ID: Date: Fri, 11 Nov 2016 07:48:31 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3656 Lines: 102 On 10/11/16 19:03, Olof Johansson wrote: > On Thu, Nov 10, 2016 at 6:34 AM, Sudeep Holla wrote: >> >> >> On 10/11/16 14:12, Rob Herring wrote: >>> >>> On Thu, Nov 10, 2016 at 4:26 AM, Sudeep Holla >>> wrote: >>>> >>>> >>>> >>>> On 10/11/16 01:22, Rob Herring wrote: >>>>> >>>>> >>>>> On Wed, Nov 02, 2016 at 10:52:09PM -0600, Sudeep Holla wrote: >>>>>> >>>>>> >>>>>> This patch adds specific compatible to support legacy SCPI protocol. >>>>>> >>>>>> Cc: Rob Herring >>>>>> Signed-off-by: Sudeep Holla >>>>>> --- >>>>>> Documentation/devicetree/bindings/arm/arm,scpi.txt | 4 +++- >>>>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/Documentation/devicetree/bindings/arm/arm,scpi.txt >>>>>> b/Documentation/devicetree/bindings/arm/arm,scpi.txt >>>>>> index d1882c4540d0..ebd03fc93135 100644 >>>>>> --- a/Documentation/devicetree/bindings/arm/arm,scpi.txt >>>>>> +++ b/Documentation/devicetree/bindings/arm/arm,scpi.txt >>>>>> @@ -7,7 +7,9 @@ by Linux to initiate various system control and power >>>>>> operations. >>>>>> >>>>>> Required properties: >>>>>> >>>>>> -- compatible : should be "arm,scpi" >>>>>> +- compatible : should be >>>>>> + * "arm,scpi" : For implementations complying to SCPI v1.0 or >>>>>> above >>>>>> + * "arm,legacy-scpi" : For implementations complying pre SCPI >>>>>> v1.0 >>>>> >>>>> >>>>> >>>>> I'd prefer that we explicitly enumerate the old versions. Are there >>>>> many? >>>>> >>>> >>>> I understand your concern, but this legacy SCPI protocol was not >>>> officially released. It was just WIP which vendors picked up from very >>>> early releases. Since they are not numbered, it's hard to have specific >>>> compatibles with different versions until v1.0. That's one of the reason >>>> to retain platform specific compatible so that we can add any quirks >>>> based on them if needed. >>>> >>>> I will probably add these information in the commit log so that it's >>>> clear why we can't do version based compatible. >>> >>> >>> This is exactly my point. By enumerate, I meant having platform >>> specific compatibles. Having "arm,legacy-scpi" is pointless because >>> who knows what version they followed and they may all be different. >>> >> >> OK, but IIUC Olof's concern wanted a generic one along with the platform >> specific compatible which kind of makes sense as so far we have seen >> some commonality between Amlogic and Rockchip. >> >> E.g. Amlogic follows most of the legacy protocol though it deviates in >> couple of things which we can handle with platform specific compatible >> (in the following patch in the series). When another user(Rockchip ?) >> make use of this legacy protocol, we can start using those platform >> specific compatible for deviations only. >> >> Is that not acceptable ? > > If there's no shared legacy feature set, then it's probably less > useful to have a shared less precise compatible value. > There is and will be some shared feature set for sure. At the least the standard command set will be shared. > What the main point I was trying to get across was that we shouldn't > expand the generic binding with per-vendor compatible fields, instead > we should have those as extensions on the side. > Yes I get the point. We will have per-vendor compatibles for handle the deviations but generic one to handle the shared set. > I'm also a little apprehensive of using "legacy", it goes in the same > bucket as "misc". At some point 1.0 will be legacy too, etc. > True and I agree, how about "arm,scpi-pre-1.0" instead ? -- Regards, Sudeep