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

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Date:   Fri, 19 Jul 2019 05:14:26 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Chanwoo Choi <cw00.choi@...sung.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

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.