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Subject: Re: [PATCH v2 4/4] arm64: dts: add support for A1 based Amlogic AD401
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>
CC:     Kevin Hilman <khilman@baylibre.com>,
        <linux-amlogic@lists.infradead.org>,
        Rob Herring <robh+dt@kernel.org>,
        Carlo Caione <carlo@caione.org>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, Jian Hu <jian.hu@amlogic.com>,
        Hanjie Lin <hanjie.lin@amlogic.com>,
        Xingyu Chen <xingyu.chen@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        Qiufang Dai <qiufang.dai@amlogic.com>,
        Tao Zeng <tao.zeng@amlogic.com>
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From:   Jianxin Pan <jianxin.pan@amlogic.com>
Message-ID: <09d7f5cc-9063-28f4-b68f-79f21fca500b@amlogic.com>
Date:   Wed, 11 Sep 2019 15:37:02 +0800
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Hi Martin,

On 2019/9/10 1:24, Martin Blumenstingl wrote:
> Hi Jianxin,
> 
> On Mon, Sep 9, 2019 at 2:03 PM Jianxin Pan <jianxin.pan@amlogic.com> wrote:
>>
>> Hi Martin,
>>
>> On 2019/9/7 23:02, Martin Blumenstingl wrote:
>>> Hi Jianxin,
>>>
>>> On Fri, Sep 6, 2019 at 7:58 AM Jianxin Pan <jianxin.pan@amlogic.com> wrote:
>>> [...]
>>>>> also I'm a bit surprised to see no busses (like aobus, cbus, periphs, ...) here
>>>>> aren't there any busses defined in the A1 SoC implementation or are
>>>>> were you planning to add them later?
>>>> Unlike previous series,there is no Cortex-M3 AO CPU in A1, and there is no AO/EE power domain.
>>>> Most of the registers are on the apb_32b bus.  aobus, cbus and periphs are not used in A1.
>>> OK, thank you for the explanation
>>> since you're going to re-send the patch anyways: can you please
>>> include the apb_32b bus?
>>> all other upstream Amlogic .dts are using the bus definitions, so that
>>> will make A1 consistent with the other SoCs
>> In A1 (and the later C1), BUS is not mentioned in the memmap and register spec.
>> Registers are organized and grouped by functions, and we can not find information about buses from the SoC document.
> do you know why the busses are not part of the documentation?
> 
>> Maybe it's better to remove bus definitions for these chips.
> my understanding is that devicetree describes the hardware
> so if there's a bus in hardware (that we know about) then we should
> describe it in devicetree
> 
> personally I think busses also make the .dts easier to read:
> instead of a huge .dts with all nodes on one level it's split into
> multiple smaller sub-nodes - thus making it easier to keep track of
> "where am I in this file".
> 
OK, I will add the bus description for A1.
Thank you for your suggestion.
> 
> Martin
> 
> .
>