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Subject: Re: [PATCH v5 2/3] clk: meson: add DT documentation for emmc clock
 controller
To:     Stephen Boyd <sboyd@kernel.org>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Yixun Lan <dlan@gentoo.org>
CC:     Neil Armstrong <narmstrong@baylibre.com>,
        Rob Herring <robh@kernel.org>,
        Hanjie Lin <hanjie.lin@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Yixun Lan <yixun.lan@amlogic.com>,
        <linux-kernel@vger.kernel.org>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Liang Yang <liang.yang@amlogic.com>,
        Jian Hu <jian.hu@amlogic.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Carlo Caione <carlo@caione.org>,
        <linux-amlogic@lists.infradead.org>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        <linux-clk@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        Qiufang Dai <qiufang.dai@amlogic.com>
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From:   Jianxin Pan <jianxin.pan@amlogic.com>
Message-ID: <fe4b3d70-12ae-84ae-0451-f5d67aa99fcd@amlogic.com>
Date:   Sun, 4 Nov 2018 23:39:44 +0800
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Hi Stephen,

Thank you for the review.

On 2018/11/4 11:04, Stephen Boyd wrote:
> Quoting Yixun Lan (2018-10-25 00:29:15)
>> yes, I think the documentation need to be fixed
>>
>> for the final solution, we decide to make 'mmc-clkc' an independent node
>> instead of being a sub-node of 'mmc', so both of them may exist in parallel..
>>
>> the DT part may like this:
>>
>>                         sd_emmc_c_clkc: clock-controller@7000 {
>>                                 compatible = "amlogic,axg-mmc-clkc", "syscon";
>>                                 reg = <0x0 0x7000 0x0 0x4>;
>>                                 ...
>>                         };
>>
>>                         sd_emmc_c: mmc@7000 {
>>                                 compatible = "amlogic,axg-mmc";
>>                                 reg = <0x0 0x7000 0x0 0x800>;
>>                                 ...
>>                         };
> 
> That's improper usage of DT. We don't want two devices at the same
> register offset.
sd_emmc_c_clkc is shared by nand and sd_emmc_c controller, and this clock is part of the MMC controller's register space.
 
The idea of adding the clock-controller@7000is introduced during the discussion in the NAND driver mainline effort:
https://lkml.kernel.org/r/20180628090034.0637a062@xps13
> 
> .
>