Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Subject: Re: [PATCH] m68k: atari: Make Atari ROM port I/O write macros return
 void
To:     Guenter Roeck <linux@roeck-us.net>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-m68k@lists.linux-m68k.org
References: <c15bedc83d90a14fffcd5b1b6bfb32b8a80282c5.1653057096.git.geert@linux-m68k.org>
 <286a1eef-e857-a31f-839b-00a4c835dfa9@roeck-us.net>
Cc:     linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>
From:   Michael Schmitz <schmitzmic@gmail.com>
Message-ID: <c2e45d59-4e0a-bf8a-e4db-ce3336fc9b05@gmail.com>
Date:   Sat, 21 May 2022 09:44:02 +1200
User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:45.0) Gecko/20100101
 Icedove/45.4.0
MIME-Version: 1.0
In-Reply-To: <286a1eef-e857-a31f-839b-00a4c835dfa9@roeck-us.net>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Guenter,

I wish I knew of a way to fix this mess for good... suggestions would be 
welcome.

Looks like you spotted the last remaining macros without a void cast 
here, thanks.

FWIW:
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>


Am 21.05.2022 um 02:52 schrieb Guenter Roeck:
> On 5/20/22 07:32, Geert Uytterhoeven wrote:
>> The macros implementing Atari ROM port I/O writes do not cast away their
>> output, unlike similar implementations for other I/O buses.
>> When they are combined using conditional expressions in the
>> definitions of
>> outb() and friends, this triggers sparse warnings like:
>>
>>      drivers/net/appletalk/cops.c:382:17: error: incompatible types in
>> conditional expression (different base types):
>>      drivers/net/appletalk/cops.c:382:17:    unsigned char
>>      drivers/net/appletalk/cops.c:382:17:    void
>>
>> Fix this by adding casts to "void".
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Reported-by: Guenter Roeck <linux@roeck-us.net>
>> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
>
>> ---
>> Survived m68k/allmodconfig.
>> To be queued in the m68k tree for v5.19.
>>
>> Removing the casts instead causes issues with functions propagating void
>> return values (return expression in void function), which BTW sparse
>> complains about, too.
>
> We live and learn. I didn't even know that this was valid syntax.
> I thought it might be easier to just fix that code, but coccinelle
> reports that there are hundreds of places in the kernel where this
> is done. Outch.
>
> Guenter