[linux-next:master 2767/3509] drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:5230:16: warning: no previous prototype for function 'wake_up_aux_channel'

[linux-next:master 2767/3509] drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:5230:16: warning: no previous prototype for function 'wake_up_aux_channel'

[kernel test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   60eac8672b5b6061ec07499c0f1b79f6d94311ce
commit: b473bd5fc333ab02479444dd4a51be5f5e324d97 [2767/3509] drm/amd/display: refine wake up aux in retrieve link caps
config: arm64-randconfig-r026-20221023 (attached as .config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 791a7ae1ba3efd6bca96338e10ffde557ba83920)
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://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=b473bd5fc333ab02479444dd4a51be5f5e324d97
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout b473bd5fc333ab02479444dd4a51be5f5e324d97
        # 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

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

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:5230:16: warning: no previous prototype for function 'wake_up_aux_channel' [-Wmissing-prototypes]
   enum dc_status wake_up_aux_channel(struct dc_link *link)
                  ^
   drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:5230:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   enum dc_status wake_up_aux_channel(struct dc_link *link)
   ^
   static 
   1 warning generated.


vim +/wake_up_aux_channel +5230 drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c

  5229	
> 5230	enum dc_status wake_up_aux_channel(struct dc_link *link)
  5231	{
  5232		enum dc_status status = DC_ERROR_UNEXPECTED;
  5233		uint32_t aux_channel_retry_cnt = 0;
  5234		uint8_t dpcd_power_state = '\0';
  5235	
  5236		while (status != DC_OK && aux_channel_retry_cnt < 10) {
  5237			status = core_link_read_dpcd(link, DP_SET_POWER,
  5238					&dpcd_power_state, sizeof(dpcd_power_state));
  5239	
  5240			/* Delay 1 ms if AUX CH is in power down state. Based on spec
  5241			 * section 2.3.1.2, if AUX CH may be powered down due to
  5242			 * write to DPCD 600h = 2. Sink AUX CH is monitoring differential
  5243			 * signal and may need up to 1 ms before being able to reply.
  5244			 */
  5245			if (status != DC_OK || dpcd_power_state == DP_SET_POWER_D3) {
  5246				udelay(1000);
  5247				aux_channel_retry_cnt++;
  5248			}
  5249		}
  5250	
  5251		if (status != DC_OK) {
  5252			dpcd_power_state = DP_SET_POWER_D0;
  5253			status = core_link_write_dpcd(
  5254					link,
  5255					DP_SET_POWER,
  5256					&dpcd_power_state,
  5257					sizeof(dpcd_power_state));
  5258	
  5259			dpcd_power_state = DP_SET_POWER_D3;
  5260			status = core_link_write_dpcd(
  5261					link,
  5262					DP_SET_POWER,
  5263					&dpcd_power_state,
  5264					sizeof(dpcd_power_state));
  5265			return DC_ERROR_UNEXPECTED;
  5266		}
  5267	
  5268		return DC_OK;
  5269	}
  5270	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

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