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

From: Krzysztof Kozlowski <krzk@kernel.org>
To: Stephen Boyd <sboyd@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,
	zhuyinbo <zhuyinbo@loongson.cn>
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
Subject: Re: [PATCH v13 2/2] clk: clk-loongson2: add clock controller driver support
Date: Fri, 10 Mar 2023 09:42:47 +0100	[thread overview]
Message-ID: <c03e47f7-bb26-0114-b300-357634b0e581@kernel.org> (raw)
In-Reply-To: <ec1fb4d134181a1b1859bcb884dcd494.sboyd@kernel.org>

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.

Best regards,
Krzysztof