linux-kernel - Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

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Message-ID: <56962FC2.1070101@gmail.com>
Date:	Wed, 13 Jan 2016 19:06:42 +0800
From:	Rongrong Zou <zourongrong@...il.com>
To:	liviu.dudau@....com, Arnd Bergmann <arnd@...db.de>
Cc:	Rongrong Zou <zourongrong@...wei.com>, devicetree@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Corey Minyard <minyard@....org>, gregkh@...uxfoundation.org,
	Will Deacon <will.deacon@....com>,
	linux-kernel@...r.kernel.org, linuxarm@...wei.com,
	benh@...nel.crashing.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

On 2016/1/13 18:09, liviu.dudau@....com wrote:
> On Tue, Jan 12, 2016 at 11:54:59PM +0100, Arnd Bergmann wrote:
>> On Tuesday 12 January 2016 10:14:18 liviu.dudau@....com wrote:
>>>
>>> OK, looking at of_translate_one() comments it looks like a missing "ranges" property is
>>> only accepted on PowerPC. I suggest you have an empty "ranges" property in your isa
>>> parent node, that will signal to the OF parsing code that the mapping is 1:1. Then have
>>> the IPMI node use the reg = <0x0 0xe4 4>; property values instead of reg = <0x1 0xe4 4>;
>>>
>>>
>>
>> A missing ranges property means that there is no translation, while an
>> empty ranges means a 1:1 translation to the parent bus.
>>
>> We really want the former here, as I/O port addresses are not mapped into
>> the MMIO space of the parent bus.
>
> Agree. However of_translate_one()'s behaviour doesn't match our expectations and I have no
> useful suggestions on what the right behaviour should be.
>

I had tried to modify the drivers/of/address.c to address this problem, but it looks
not so general. I'm not sure you have seen this: https://lkml.org/lkml/2016/1/10/89 .

Regards,
Rongrong