linux-kernel - Re: [PATCH] clk: mediatek: Fix all warnings for missing struct clk_onecell

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Message-ID: <20171223122002.2cb629d1@endymion>
Date:   Sat, 23 Dec 2017 12:20:02 +0100
From:   Jean Delvare <jdelvare@...e.de>
To:     <sean.wang@...iatek.com>
Cc:     <sboyd@...eaurora.org>, <mturquette@...libre.com>,
        <matthias.bgg@...il.com>, <jamesjj.liao@...iatek.com>,
        <weiyi.lu@...iatek.com>, <arnd@...db.de>,
        <linux-mediatek@...ts.infradead.org>, <linux-clk@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <kbuild-all@...org>
Subject: Re: [PATCH] clk: mediatek: Fix all warnings for missing struct
 clk_onecell_data

Hi Sean,

On Sat, 23 Dec 2017 15:56:36 +0800, sean.wang@...iatek.com wrote:
> From: Sean Wang <sean.wang@...iatek.com>
> 
> In fact, the clk-mtk.h header is unnecessary for reset.c and thus it's
> safe to remove it from the file to get rid of below build warnings.
> 
> All warnings (new ones prefixed by >>):
> 
>    In file included from drivers/clk/mediatek/reset.c:22:0:
> >>drivers/clk/mediatek/clk-mtk.h:44:19: warning: 'struct clk_onecell_data'  
> declared inside parameter list will not be visible outside of
> this definition or declaration
>       int num, struct clk_onecell_data *clk_data);
>                       ^~~~~~~~~~~~~~~~
> drivers/clk/mediatek/clk-mtk.h:63:19: warning: 'struct clk_onecell_data'
> declared inside parameter list will not be visible outside of
> this definition or declaration
>       int num, struct clk_onecell_data *clk_data);
>                       ^~~~~~~~~~~~~~~~
> drivers/clk/mediatek/clk-mtk.h:145:10: warning: 'struct clk_onecell_data'
> declared inside parameter list will not be visible outside of
> this definition or declaration
>       struct clk_onecell_data *clk_data);
>              ^~~~~~~~~~~~~~~~
> drivers/clk/mediatek/clk-mtk.h:164:11: warning: 'struct clk_onecell_data'
> declared inside parameter list will not be visible outside of
> this definition or declaration
>        struct clk_onecell_data *clk_data);
>               ^~~~~~~~~~~~~~~~
> drivers/clk/mediatek/clk-mtk.h:190:12: warning: 'struct clk_onecell_data'
> declared inside parameter list will not be visible outside of this
> definition or declaration
>         struct clk_onecell_data *clk_data);
>                ^~~~~~~~~~~~~~~~

That's not the proper fix. The actual problem here is in clk-mtk.h,
which declares functions which need struct clk_onecell_data without
declaring that structure first. This can be fixed in 2 ways:

1* #Include whatever header file provides the definition of struct
   clk_onecell_data (I think <linux/clk-provider.h>) in clk-mtk.h
   itself.

2* As you only manipulate pointers and not the structure itself, you
   could simply declare that this struct exists, without defining it,
   prior to referencing it in clk-mtk.h. As easy as:

   struct clk_onecell_data;

In this case option 1 seems preferable.

The reason why the problem is only visible in reset.c is because other
source files under drivers/clk/mediatek #include <linux/clk-provider.h>
explicitly before #including clk-mtk.h. But it only works "by
accident". Ideally header files should be self-sufficient, so you don't
depend on #include order.

> Reported-by: kbuild test robot <fengguang.wu@...el.com>
> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> Cc: kbuild-all@...org
> Cc: Stephen Boyd <sboyd@...eaurora.org>
> Cc: linux-clk@...r.kernel.org
> ---
>  drivers/clk/mediatek/reset.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/clk/mediatek/reset.c b/drivers/clk/mediatek/reset.c
> index d3551d5..70ebb2e 100644
> --- a/drivers/clk/mediatek/reset.c
> +++ b/drivers/clk/mediatek/reset.c
> @@ -19,8 +19,6 @@
>  #include <linux/reset-controller.h>
>  #include <linux/slab.h>
>  
> -#include "clk-mtk.h"
> -
>  struct mtk_reset {
>  	struct regmap *regmap;
>  	int regofs;

If the header file is indeed not needed then that's still a good
change, even if it doesn't fix the problem, so:

Reviewed-by: Jean Delvare <jdelvare@...e.de>

However the patch description should be adjusted accordingly.

-- 
Jean Delvare
SUSE L3 Support