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Subject: Re: [PATCH v1 2/2] arm: dts: mt2701: add nor flash node
To: Guochun Mao <guochun.mao@mediatek.com>
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Cc: Boris Brezillon <boris.brezillon@free-electrons.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        Rob Herring <robh@kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Richard Weinberger <richard@nod.at>,
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        Mark Rutland <mark.rutland@arm.com>,
        Brian Norris <computersforpeace@gmail.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Cyrille Pitchen <cyrille.pitchen@atmel.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
From: John Crispin <john@phrozen.org>
Message-ID: <3b86fcfd-9f8a-b324-e164-20582a0b2e40@phrozen.org>
Date: Tue, 24 Jan 2017 11:38:41 +0100
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On 24/01/2017 11:31, Boris Brezillon wrote:
> On Sun, 22 Jan 2017 10:36:40 +0800
> Guochun Mao <guochun.mao@mediatek.com> wrote:
> 
>> Hi,
>> On Thu, 2017-01-19 at 08:18 -0600, Rob Herring wrote:
>>> On Thu, Jan 19, 2017 at 2:14 AM, Boris Brezillon  
>>>> One last question and I'm done: is something like that acceptable?
>>>>
>>>>         compatible = "<vendor>,<old-soc>","<vendor>,<new-soc>";
>>>>
>>>> This can happen when someone adds support for an unsupported feature
>>>> on a brand new SoC, and then someone else use the same driver for an
>>>> older SoC embedding the same IP but still wants to add a new compatible
>>>> just in case these 2 IPs appear to be slightly different.  
>>>
>>> Yes, it's old and new compatible strings in this case and it's newest
>>> compatible string first.
>>>   
>>>> Here the order of compat strings is no longer following a clear rule
>>>> like 'most-specific compatible first' or 'newest IP/SoC version first',
>>>> it's completely dependent on the order these IPs were supported in the
>>>> OS (Linux). I'm perfectly fine with that BTW, just want to make sure
>>>> this is authorized.  
>>>
>>> I guess we should say "newest compatible for IP first" instead. There
>>> are some exceptions where we add fallbacks later on, but that falls
>>> under the most-specific part.
>>>
>>> It's order that the bindings are defined, not Linux support really,
>>> but in practice those are the same.
>>>
>>> Rob  
>>
>> Thanks for all your effort for code reviewing.
>> Our mt2701-nor's hardware is designed base on mt8713-nor,
>> even so, there would be some slight difference.
>> If I don't misunderstand your viewpoint in this discussion,
>> there's no need to drop mt2701-nor compatible.
> 
> No, just update the documentation as suggested by Rob.
> 
>> And if not, is there any other suggestion?
> 
> Nope, and my apologies for being so insistent on something I obviously
> misunderstood.
> 
> Regards,
> 
> Boris


Hi,

could you please add the mt7623 compat string to the documentation
aswell while at it ? mt7623/mt2701 are essentially the same and it'll
safe us time and effort and not cause merge order conflicts. otherwise i
would need to wait till the mt2701 patch is merged before i can send the
mt7623 one

Thanks !
	John