arch/arm/mach-lpc32xx/serial.c:63:6: warning: no previous prototype for 'lpc32xx_loopback_set'

[kernel test robot]

Hi Arnd,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   6bfb56e93bcef41859c2d5ab234ffd80b691be35
commit: 7036440eab3e2d47a775d4616909f8235488d714 ARM: omap1: enable multiplatform
date:   6 days ago
config: arm-buildonly-randconfig-r012-20220608 (https://download.01.org/0day-ci/archive/20220610/202206100243.FIBW6bJC-lkp@xxxxxxxxx/config)
compiler: arm-linux-gnueabi-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7036440eab3e2d47a775d4616909f8235488d714
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 7036440eab3e2d47a775d4616909f8235488d714
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> arch/arm/mach-lpc32xx/serial.c:63:6: warning: no previous prototype for 'lpc32xx_loopback_set' [-Wmissing-prototypes]
      63 | void lpc32xx_loopback_set(resource_size_t mapbase, int state)
         |      ^~~~~~~~~~~~~~~~~~~~


vim +/lpc32xx_loopback_set +63 arch/arm/mach-lpc32xx/serial.c

e6e912c4964ce5 Kevin Wells   2010-07-27  61  
ffba29c9ebd097 Arnd Bergmann 2019-08-09  62  /* LPC3250 Errata HSUART.1: Hang workaround via loopback mode on inactivity */
ffba29c9ebd097 Arnd Bergmann 2019-08-09 @63  void lpc32xx_loopback_set(resource_size_t mapbase, int state)
ffba29c9ebd097 Arnd Bergmann 2019-08-09  64  {
ffba29c9ebd097 Arnd Bergmann 2019-08-09  65  	int bit;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  66  	u32 tmp;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  67  
ffba29c9ebd097 Arnd Bergmann 2019-08-09  68  	switch (mapbase) {
ffba29c9ebd097 Arnd Bergmann 2019-08-09  69  	case LPC32XX_HS_UART1_BASE:
ffba29c9ebd097 Arnd Bergmann 2019-08-09  70  		bit = 0;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  71  		break;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  72  	case LPC32XX_HS_UART2_BASE:
ffba29c9ebd097 Arnd Bergmann 2019-08-09  73  		bit = 1;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  74  		break;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  75  	case LPC32XX_HS_UART7_BASE:
ffba29c9ebd097 Arnd Bergmann 2019-08-09  76  		bit = 6;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  77  		break;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  78  	default:
ffba29c9ebd097 Arnd Bergmann 2019-08-09  79  		WARN(1, "lpc32xx_hs: Warning: Unknown port at %08x\n", mapbase);
ffba29c9ebd097 Arnd Bergmann 2019-08-09  80  		return;
ffba29c9ebd097 Arnd Bergmann 2019-08-09  81  	}
ffba29c9ebd097 Arnd Bergmann 2019-08-09  82  
ffba29c9ebd097 Arnd Bergmann 2019-08-09  83  	tmp = readl(LPC32XX_UARTCTL_CLOOP);
ffba29c9ebd097 Arnd Bergmann 2019-08-09  84  	if (state)
ffba29c9ebd097 Arnd Bergmann 2019-08-09  85  		tmp |= (1 << bit);
ffba29c9ebd097 Arnd Bergmann 2019-08-09  86  	else
ffba29c9ebd097 Arnd Bergmann 2019-08-09  87  		tmp &= ~(1 << bit);
ffba29c9ebd097 Arnd Bergmann 2019-08-09  88  	writel(tmp, LPC32XX_UARTCTL_CLOOP);
ffba29c9ebd097 Arnd Bergmann 2019-08-09  89  }
ffba29c9ebd097 Arnd Bergmann 2019-08-09  90  EXPORT_SYMBOL_GPL(lpc32xx_loopback_set);
ffba29c9ebd097 Arnd Bergmann 2019-08-09  91  

:::::: The code at line 63 was first introduced by commit
:::::: ffba29c9ebd0977dbf77bf6064776716a51b8ae5 serial: lpc32xx: allow compile testing

:::::: TO: Arnd Bergmann <arnd@xxxxxxxx>
:::::: CC: Arnd Bergmann <arnd@xxxxxxxx>

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