linux-kernel - RE: [PATCH V4 3/5] clk: imx: Support building i.MX common clock driver as module

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Date:   Thu, 2 Jul 2020 06:11:13 +0000
From:   Anson Huang <anson.huang@....com>
To:     Dong Aisheng <dongas86@...il.com>
CC:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        Peng Fan <peng.fan@....com>, Arnd Bergmann <arnd@...db.de>,
        Abel Vesa <abel.vesa@....com>,
        Aisheng Dong <aisheng.dong@....com>,
        Andy Duan <fugang.duan@....com>,
        Daniel Baluta <daniel.baluta@....com>,
        YueHaibing <yuehaibing@...wei.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        linux-clk <linux-clk@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V4 3/5] clk: imx: Support building i.MX common clock
 driver as module



> Subject: Re: [PATCH V4 3/5] clk: imx: Support building i.MX common clock
> driver as module
> 
> On Thu, Jul 2, 2020 at 11:26 AM Anson Huang <anson.huang@....com>
> wrote:
> [...]
> > > > @@ -143,16 +148,18 @@ void imx_cscmr1_fixup(u32 *val)  static int
> > > > imx_keep_uart_clocks;  static struct clk ** const
> > > > *imx_uart_clocks;
> > > >
> > > > -static int __init imx_keep_uart_clocks_param(char *str)
> > > > +static int __maybe_unused imx_keep_uart_clocks_param(char *str)
> > > >  {
> > > >         imx_keep_uart_clocks = 1;
> > > >
> > > >         return 0;
> > > >  }
> > > > +#ifndef MODULE
> > > >  __setup_param("earlycon", imx_keep_uart_earlycon,
> > > >               imx_keep_uart_clocks_param, 0);
> > > > __setup_param("earlyprintk", imx_keep_uart_earlyprintk,
> > > >               imx_keep_uart_clocks_param, 0);
> > >
> > > I feel not only the __setup_param, the whole logic of
> > > keep_uart_clocks are not needed for Module case. Is it true?
> >
> > Yes, but the 'keep_uart_clocks' is false by default and the function
> > imx_keep_uart_clocks_param() already has '__maybe_unused', it does NOT
> > impact anything if it is for module build, so I did NOT add the #ifndef check
> for them, just to keep code easy and clean.
> >
> 
> IMHO do not compile them is a more easy and clean way. Then users don't
> have to look into the code logic which is meaingless for Module case.
> 
> BTW, it really does not make any sense to only condionally compile
> __setup_parm() but left
> the param functions definition to be handled by __maybe_unnused.
> They're together part of code, aren't they?

I am fine of adding the '#ifndef MODULE' to imx_clk_disable_uart() and imx_keep_uart_clocks_param()
as well in next patch series. Others like ' imx_keep_uart_clocks ' and imx_register_uart_clocks() need to
be kept always built, since they are used by each clock driver no matter built-in or module build.

So that means I have to add another 'ifndef MODULE' or I need to adjust some code sequence to make
those code can be built-out in same block and just use single 'ifndef MODULE', I think adjust the code
sequence should be better, will go with this way.

Anson