linux-kernel - [PATCH] m68k: atari: Make Atari ROM port I/O write macros return void

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Message-Id: <c15bedc83d90a14fffcd5b1b6bfb32b8a80282c5.1653057096.git.geert@linux-m68k.org>
Date:   Fri, 20 May 2022 16:32:30 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     linux-m68k@...ts.linux-m68k.org
Cc:     Guenter Roeck <linux@...ck-us.net>, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        kernel test robot <lkp@...el.com>
Subject: [PATCH] m68k: atari: Make Atari ROM port I/O write macros return void

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@...el.com>
Reported-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
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.
---
 arch/m68k/include/asm/raw_io.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/m68k/include/asm/raw_io.h b/arch/m68k/include/asm/raw_io.h
index 80eb2396d01ebf61..3ba40bc1dfaa9471 100644
--- a/arch/m68k/include/asm/raw_io.h
+++ b/arch/m68k/include/asm/raw_io.h
@@ -80,14 +80,14 @@
 	({ u16 __v = le16_to_cpu(*(__force volatile u16 *) (addr)); __v; })
 
 #define rom_out_8(addr, b)	\
-	({u8 __maybe_unused __w, __v = (b);  u32 _addr = ((u32) (addr)); \
+	(void)({u8 __maybe_unused __w, __v = (b);  u32 _addr = ((u32) (addr)); \
 	__w = ((*(__force volatile u8 *)  ((_addr | 0x10000) + (__v<<1)))); })
 #define rom_out_be16(addr, w)	\
-	({u16 __maybe_unused __w, __v = (w); u32 _addr = ((u32) (addr)); \
+	(void)({u16 __maybe_unused __w, __v = (w); u32 _addr = ((u32) (addr)); \
 	__w = ((*(__force volatile u16 *) ((_addr & 0xFFFF0000UL) + ((__v & 0xFF)<<1)))); \
 	__w = ((*(__force volatile u16 *) ((_addr | 0x10000) + ((__v >> 8)<<1)))); })
 #define rom_out_le16(addr, w)	\
-	({u16 __maybe_unused __w, __v = (w); u32 _addr = ((u32) (addr)); \
+	(void)({u16 __maybe_unused __w, __v = (w); u32 _addr = ((u32) (addr)); \
 	__w = ((*(__force volatile u16 *) ((_addr & 0xFFFF0000UL) + ((__v >> 8)<<1)))); \
 	__w = ((*(__force volatile u16 *) ((_addr | 0x10000) + ((__v & 0xFF)<<1)))); })
 
-- 
2.25.1