arch/m68k/coldfire/m523x.c:82:20: error: implicit declaration of function 'read8'; did you mean 'readb'?

From: kernel test robot

Date: Fri Jul 03 2026 - 17:14:56 EST


Hi Greg,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: d2c9a99135da931377240942d44f3dea104cedb8
commit: e1f3a00670d13d1ed901125026c1f65394e670a5 m68k: coldfire: use ColdFire specifc IO access in SoC code
date: 4 weeks ago
config: m68k-randconfig-r122-20260704 (https://download.01.org/0day-ci/archive/20260704/202607040536.BiSGmESw-lkp@xxxxxxxxx/config)
compiler: m68k-linux-gcc (GCC) 15.2.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260704/202607040536.BiSGmESw-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: e1f3a00670d1 ("m68k: coldfire: use ColdFire specifc IO access in SoC code")
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202607040536.BiSGmESw-lkp@xxxxxxxxx/

All errors (new ones prefixed by >>):

In file included from arch/m68k/include/asm/io.h:6,
from include/linux/io.h:12,
from arch/m68k/coldfire/m523x.c:20:
arch/m68k/coldfire/m523x.c: In function 'm523x_fec_init':
>> arch/m68k/coldfire/m523x.c:82:20: error: implicit declaration of function 'read8'; did you mean 'readb'? [-Wimplicit-function-declaration]
82 | mcf_write8(read8(MCFGPIO_PAR_FECI2C) | 0xf0, MCFGPIO_PAR_FECI2C);
| ^~~~~
arch/m68k/include/asm/io_no.h:23:75: note: in definition of macro '__raw_writeb'
23 | #define __raw_writeb(b, addr) (void)((*(__force volatile u8 *) (addr)) = (b))
| ^
arch/m68k/coldfire/m523x.c:82:9: note: in expansion of macro 'mcf_write8'
82 | mcf_write8(read8(MCFGPIO_PAR_FECI2C) | 0xf0, MCFGPIO_PAR_FECI2C);
| ^~~~~~~~~~


vim +82 arch/m68k/coldfire/m523x.c

78
79 static void __init m523x_fec_init(void)
80 {
81 /* Set multi-function pins to ethernet use */
> 82 mcf_write8(read8(MCFGPIO_PAR_FECI2C) | 0xf0, MCFGPIO_PAR_FECI2C);
83 }
84

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https://github.com/intel/lkp-tests/wiki