arch/powerpc/boot/decompress.c:132:8: error: call to undeclared function '__decompress'; ISO C99 and later do not support implicit function declarations

[kernel test robot <lkp@intel.com>]

Hi Dan,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   aaf724ed69264719550ec4f194d3ab17b886af9a
commit: 3d6ebf16438de5d712030fefbb4182b46373d677 cxl/port: Fix cxl_bus_rescan() vs bus_rescan_devices()
date:   8 months ago
config: powerpc64-randconfig-r054-20250628 (https://download.01.org/0day-ci/archive/20250628/202506281959.PtSsiYM8-lkp@intel.com/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project e04c938cc08a90ae60440ce22d072ebc69d67ee8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250628/202506281959.PtSsiYM8-lkp@intel.com/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
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506281959.PtSsiYM8-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/powerpc/boot/decompress.c:132:8: error: call to undeclared function '__decompress'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     132 |         ret = __decompress(inbuf, input_size, NULL, flush, outbuf,
         |               ^
   1 error generated.


vim +/__decompress +132 arch/powerpc/boot/decompress.c

1b7898ee276b39 Oliver O'Halloran 2016-09-22   97  
1b7898ee276b39 Oliver O'Halloran 2016-09-22   98  /**
1b7898ee276b39 Oliver O'Halloran 2016-09-22   99   * partial_decompress - decompresses part or all of a compressed buffer
1b7898ee276b39 Oliver O'Halloran 2016-09-22  100   * @inbuf:       input buffer
1b7898ee276b39 Oliver O'Halloran 2016-09-22  101   * @input_size:  length of the input buffer
930a77c3ad79c3 Zhang Jianhua     2021-05-10  102   * @outbuf:      output buffer
930a77c3ad79c3 Zhang Jianhua     2021-05-10  103   * @output_size: length of the output buffer
6efc2f1a64ef62 Yang Li           2024-04-08  104   * @_skip:       number of output bytes to ignore
1b7898ee276b39 Oliver O'Halloran 2016-09-22  105   *
1b7898ee276b39 Oliver O'Halloran 2016-09-22  106   * This function takes compressed data from inbuf, decompresses and write it to
1b7898ee276b39 Oliver O'Halloran 2016-09-22  107   * outbuf. Once output_size bytes are written to the output buffer, or the
1b7898ee276b39 Oliver O'Halloran 2016-09-22  108   * stream is exhausted the function will return the number of bytes that were
1b7898ee276b39 Oliver O'Halloran 2016-09-22  109   * decompressed. Otherwise it will return whatever error code the decompressor
1b7898ee276b39 Oliver O'Halloran 2016-09-22  110   * reported (NB: This is specific to each decompressor type).
1b7898ee276b39 Oliver O'Halloran 2016-09-22  111   *
1b7898ee276b39 Oliver O'Halloran 2016-09-22  112   * The skip functionality is mainly there so the program and discover
1b7898ee276b39 Oliver O'Halloran 2016-09-22  113   * the size of the compressed image so that it can ask firmware (if present)
1b7898ee276b39 Oliver O'Halloran 2016-09-22  114   * for an appropriately sized buffer.
1b7898ee276b39 Oliver O'Halloran 2016-09-22  115   */
1b7898ee276b39 Oliver O'Halloran 2016-09-22  116  long partial_decompress(void *inbuf, unsigned long input_size,
1b7898ee276b39 Oliver O'Halloran 2016-09-22  117  	void *outbuf, unsigned long output_size, unsigned long _skip)
1b7898ee276b39 Oliver O'Halloran 2016-09-22  118  {
1b7898ee276b39 Oliver O'Halloran 2016-09-22  119  	int ret;
1b7898ee276b39 Oliver O'Halloran 2016-09-22  120  
1b7898ee276b39 Oliver O'Halloran 2016-09-22  121  	/*
1b7898ee276b39 Oliver O'Halloran 2016-09-22  122  	 * The skipped bytes needs to be included in the size of data we want
1b7898ee276b39 Oliver O'Halloran 2016-09-22  123  	 * to decompress.
1b7898ee276b39 Oliver O'Halloran 2016-09-22  124  	 */
1b7898ee276b39 Oliver O'Halloran 2016-09-22  125  	output_size += _skip;
1b7898ee276b39 Oliver O'Halloran 2016-09-22  126  
1b7898ee276b39 Oliver O'Halloran 2016-09-22  127  	decompressed_bytes = 0;
1b7898ee276b39 Oliver O'Halloran 2016-09-22  128  	output_buffer = outbuf;
1b7898ee276b39 Oliver O'Halloran 2016-09-22  129  	limit = output_size;
1b7898ee276b39 Oliver O'Halloran 2016-09-22  130  	skip = _skip;
1b7898ee276b39 Oliver O'Halloran 2016-09-22  131  
1b7898ee276b39 Oliver O'Halloran 2016-09-22 @132  	ret = __decompress(inbuf, input_size, NULL, flush, outbuf,

:::::: The code at line 132 was first introduced by commit
:::::: 1b7898ee276b39e54d870dc4ef3374f663d0b426 powerpc/boot: Use the pre-boot decompression API

:::::: TO: Oliver O'Halloran <oohall@gmail.com>
:::::: CC: Michael Ellerman <mpe@ellerman.id.au>

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