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Sender: Guenter Roeck <groeck7@gmail.com>
Date:   Sat, 29 Oct 2022 07:25:51 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: [PATCH v1 2/2] Input: matrix_keypad - replace header inclusions
 by forward declarations
Message-ID: <20221029142551.GA3222119@roeck-us.net>
References: <20220923184632.2157-1-andriy.shevchenko@linux.intel.com>
 <20220923184632.2157-2-andriy.shevchenko@linux.intel.com>
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In-Reply-To: <20220923184632.2157-2-andriy.shevchenko@linux.intel.com>
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On Fri, Sep 23, 2022 at 09:46:32PM +0300, Andy Shevchenko wrote:
> When the data structure is only referred by pointer, compiler may not need
> to see the contents of the data type. Thus, we may replace header inclusions
> by respective forward declarations.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  include/linux/input/matrix_keypad.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/input/matrix_keypad.h b/include/linux/input/matrix_keypad.h
> index 9476768c3b90..b8d8d69eba29 100644
> --- a/include/linux/input/matrix_keypad.h
> +++ b/include/linux/input/matrix_keypad.h
> @@ -3,8 +3,9 @@
>  #define _MATRIX_KEYPAD_H
>  
>  #include <linux/types.h>
> -#include <linux/input.h>

Possibly, but may other drivers rely on those includes.
This results in widespread build failures such as

Building arm:allmodconfig ... failed
--------------
Error log:
In file included from include/linux/input/samsung-keypad.h:12,
                 from arch/arm/mach-s3c/keypad.h:12,
                 from arch/arm/mach-s3c/mach-crag6410.c:57:
arch/arm/mach-s3c/mach-crag6410.c:183:19: error: 'KEY_VOLUMEUP' undeclared here

Guenter