linux-kernel - Re: [PATCH v13 2/2] clk: clk-loongson2: add clock controller driver support

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Message-ID: <958bfe5b-c7c5-3373-a904-d9a32b428e02@loongson.cn>
Date:   Tue, 14 Mar 2023 09:07:16 +0800
From:   zhuyinbo <zhuyinbo@...ngson.cn>
To:     Stephen Boyd <sboyd@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        kernel test robot <lkp@...el.com>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     oe-kbuild-all@...ts.linux.dev, Jianmin Lv <lvjianmin@...ngson.cn>,
        Liu Peibao <liupeibao@...ngson.cn>, wanghongliang@...ngson.cn,
        loongson-kernel@...ts.loongnix.cn, zhuyinbo@...ngson.cn
Subject: Re: [PATCH v13 2/2] clk: clk-loongson2: add clock controller driver
 support


在 2023/3/14 上午2:20, Stephen Boyd 写道:
> Quoting Krzysztof Kozlowski (2023-03-10 00:42:47)
>> On 10/03/2023 00:47, Stephen Boyd wrote:
>>> Quoting zhuyinbo (2023-03-08 18:58:02)
>>>> 在 2023/3/8 下午8:16, kernel test robot 写道:
>>>>> Hi Yinbo,
>>>>>
>>> [...]
>>>>>      drivers/clk/clk-loongson2.c: In function 'loongson2_calc_pll_rate':
>>>>>>> drivers/clk/clk-loongson2.c:79:15: error: implicit declaration of function 'readq'; did you mean 'readl'? [-Werror=implicit-function-declaration]
>>>>>         79 |         val = readq(loongson2_pll_base + offset);
>>>>>            |               ^~~~~
>>>>>            |               readl
>>>>>      cc1: some warnings being treated as errors
>>>> The CONFIG_64BIT not enabled in your config file, I will add a depend on
>>>> "CONFIG_64BIT" in my clock driver to fix this compile error.
>>> Do you need to use readq() here? Can you read two 32-bit registers with
>>> readl() and put them together for a 64-bit number?
>> If the platform supports 64-bit reads and these are actually one
>> register, then readq makes sense - code is more readable, smaller, more
>> efficient.
>>
> Please read the section in Documentation/driver-api/device-io.rst about
> hi_lo_readq() and <linux/io-64-nonatomic-lo-hi.h>. We shouldn't need to
> restrict the driver to CONFIG_64BIT. Instead, include one of these
> header files to get the IO access primitives.

okay, I got it.

Thanks your advice!