[asahilinux:bits/070-audio 2/20] drivers/dma/apple-admac.c:260:5: warning: no previous prototype for function 'admac_cyclic_read_residue'

[kernel test robot]

tree:   https://github.com/AsahiLinux/linux bits/070-audio
head:   401ef594286e6abfe89c2d92664087bc5d6ca657
commit: d2b3a34a7f529cd3e338989d7b4c71981180ad30 [2/20] dmaengine: apple-admac: Add Apple ADMAC driver
config: arm64-buildonly-randconfig-r005-20220524 (https://download.01.org/0day-ci/archive/20220525/202205251600.AqjYQGzD-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d52a6e75b0c402c7f3b42a2b1b2873f151220947)
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
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://github.com/AsahiLinux/linux/commit/d2b3a34a7f529cd3e338989d7b4c71981180ad30
        git remote add asahilinux https://github.com/AsahiLinux/linux
        git fetch --no-tags asahilinux bits/070-audio
        git checkout d2b3a34a7f529cd3e338989d7b4c71981180ad30
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/dma/

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

All warnings (new ones prefixed by >>):

>> drivers/dma/apple-admac.c:260:5: warning: no previous prototype for function 'admac_cyclic_read_residue' [-Wmissing-prototypes]
   u32 admac_cyclic_read_residue(struct admac_data *ad, int channo, struct admac_tx *adtx)
       ^
   drivers/dma/apple-admac.c:260:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   u32 admac_cyclic_read_residue(struct admac_data *ad, int channo, struct admac_tx *adtx)
   ^
   static 
   1 warning generated.


vim +/admac_cyclic_read_residue +260 drivers/dma/apple-admac.c

   256	
   257	/*
   258	 * Read from hardware the residue of a cyclic dmaengine transaction.
   259	 */
 > 260	u32 admac_cyclic_read_residue(struct admac_data *ad, int channo, struct admac_tx *adtx)
   261	{
   262		u32 ring1, ring2;
   263		u32 residue1, residue2;
   264		int nreports;
   265		size_t pos;
   266	
   267		ring1 =    admac_peek(ad, REG_REPORT_RING(channo));
   268		residue1 = admac_peek(ad, REG_RESIDUE(channo));
   269		ring2 =    admac_peek(ad, REG_REPORT_RING(channo));
   270		residue2 = admac_peek(ad, REG_RESIDUE(channo));
   271	
   272		if (residue2 > residue1) {
   273			// engine must have loaded next descriptor between the two residue reads
   274			nreports = admac_ring_noccupied_slots(ring1) + 1;
   275		} else {
   276			// no descriptor load between the two reads, ring2 is safe to use
   277			nreports = admac_ring_noccupied_slots(ring2);
   278		}
   279	
   280		pos = adtx->reclaimed_pos + adtx->period_len * (nreports + 1) \
   281							 - residue2;
   282	
   283		return adtx->buf_len - pos % adtx->buf_len;
   284	}
   285	

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