linux-kernel - Re: [PATCH v4 12/24] PM / devfreq: tegra30: Inline all one-line functions

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Date:   Fri, 19 Jul 2019 15:01:50 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 12/24] PM / devfreq: tegra30: Inline all one-line
 functions

On 19. 7. 19. 오전 11:14, Dmitry Osipenko wrote:
> В Fri, 19 Jul 2019 10:27:16 +0900
> Chanwoo Choi <cw00.choi@...sung.com> пишет:
> 
>> On 19. 7. 19. 오전 10:24, Chanwoo Choi wrote:
>>> On 19. 7. 19. 오전 10:22, Dmitry Osipenko wrote:  
>>>> В Thu, 18 Jul 2019 18:09:05 +0900
>>>> Chanwoo Choi <cw00.choi@...sung.com> пишет:
>>>>  
>>>>> On 19. 7. 16. 오후 10:35, Dmitry Osipenko wrote:  
>>>>>> 16.07.2019 15:26, Chanwoo Choi пишет:    
>>>>>>> Hi Dmitry,
>>>>>>>
>>>>>>> I'm not sure that it is necessary.
>>>>>>> As I knew, usally, the 'inline' is used on header file
>>>>>>> to define the empty functions.
>>>>>>>
>>>>>>> Do we have to change it with 'inline' keyword?    
>>>>>>
>>>>>> The 'inline' attribute tells compiler that instead of jumping
>>>>>> into the function, it should take the function's code and
>>>>>> replace the function's invocation with that code. This is done
>>>>>> in order to help compiler optimize code properly, please see
>>>>>> [1]. There is absolutely no need to create a function call into
>>>>>> a function that consists of a single instruction.
>>>>>>
>>>>>> [1] https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Inline.html
>>>>>>     
>>>>>
>>>>> If you want to add 'inline' keyword, I recommend that 
>>>>> you better to remove the modified function in this patch
>>>>> and then just call the 'write_relaxed or read_relaxed' function
>>>>> directly. It is same result when using inline keyword.  
>>>>
>>>> That could be done, but it makes code less readable.
>>>>
>>>> See the difference:
>>>>
>>>> device_writel(dev, ACTMON_INTR_STATUS_CLEAR,
>>>> ACTMON_DEV_INTR_STATUS);
>>>>
>>>> writel_relaxed(ACTMON_INTR_STATUS_CLEAR,
>>>> 	       dev->regs + ACTMON_DEV_INTR_STATUS);  
>>>
>>> No problem if you add the detailed comment and you want to use
>>> the 'inline' keyword.  
>>
>> Basically, I think that 'inline' keyword is not necessary.
> 
> Sure, but I'm finding that it's always nicer to explicitly inline a very
> simple functions because compiler may not do it properly itself in some
> cases.
> 
>> But if you want to use 'inline' keyword, I recommend
>> that call the 'write_relaxed or read_relaxed' function directly
>> with detailed description. 
> 
> Could you please reword this sentence? Not sure that I'm understanding
> it correctly.
> 

If you want to used 'inline' keyword,
Instead, I recommend that remove 'actmon_readl/writel' wrapper functions
and then you calls 'write_relaxed or read_relaxed' function directly
with detailed description.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics