Subject: Re: [PATCH v13 2/2] clk: clk-loongson2: add clock controller driver
 support
To:     Stephen Boyd <sboyd@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Rob Herring <robh+dt@kernel.org>, devicetree@vger.kernel.org,
        kernel test robot <lkp@intel.com>, linux-clk@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     oe-kbuild-all@lists.linux.dev, Jianmin Lv <lvjianmin@loongson.cn>,
        Liu Peibao <liupeibao@loongson.cn>, wanghongliang@loongson.cn,
        loongson-kernel@lists.loongnix.cn, zhuyinbo@loongson.cn
References: <20230307115022.12846-2-zhuyinbo@loongson.cn>
 <202303082037.QPfBP64A-lkp@intel.com>
 <b94ee1d2-b224-f9d5-3f3c-0096634f4c93@loongson.cn>
 <ec1fb4d134181a1b1859bcb884dcd494.sboyd@kernel.org>
 <c03e47f7-bb26-0114-b300-357634b0e581@kernel.org>
 <61eee19400e9a45ce9543bfd92a27eaa.sboyd@kernel.org>
From:   zhuyinbo <zhuyinbo@loongson.cn>
Message-ID: <958bfe5b-c7c5-3373-a904-d9a32b428e02@loongson.cn>
Date:   Tue, 14 Mar 2023 09:07:16 +0800
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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!