Hi Jimmy, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 3e029760e6f8ce90c122c267a039ae73b3f1f5a4 commit: 7211b60514f88e695080ebc4074c6affd880acb8 [5435/5886] drm/amd/display: Update DP link configuration. config: powerpc-randconfig-r023-20210528 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 6505c630407c5feec818f0bb1c284f9eeebf2071) 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 powerpc cross compiling tool for clang build # apt-get install binutils-powerpc-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=7211b60514f88e695080ebc4074c6affd880acb8 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 7211b60514f88e695080ebc4074c6affd880acb8 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:1372:16: warning: no previous prototype for function 'configure_lttpr_mode_transparent' [-Wmissing-prototypes] enum dc_status configure_lttpr_mode_transparent(struct dc_link *link) ^ drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:1372:1: note: declare 'static' if the function is not intended to be used outside of this translation unit enum dc_status configure_lttpr_mode_transparent(struct dc_link *link) ^ static >> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:1383:16: warning: no previous prototype for function 'configure_lttpr_mode_non_transparent' [-Wmissing-prototypes] enum dc_status configure_lttpr_mode_non_transparent( ^ drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:1383:1: note: declare 'static' if the function is not intended to be used outside of this translation unit enum dc_status configure_lttpr_mode_non_transparent( ^ static 2 warnings generated. vim +/configure_lttpr_mode_transparent +1372 drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c 1371 > 1372 enum dc_status configure_lttpr_mode_transparent(struct dc_link *link) 1373 { 1374 uint8_t repeater_mode = DP_PHY_REPEATER_MODE_TRANSPARENT; 1375 1376 DC_LOG_HW_LINK_TRAINING("%s\n Set LTTPR to Transparent Mode\n", __func__); 1377 return core_link_write_dpcd(link, 1378 DP_PHY_REPEATER_MODE, 1379 (uint8_t *)&repeater_mode, 1380 sizeof(repeater_mode)); 1381 } 1382 > 1383 enum dc_status configure_lttpr_mode_non_transparent( 1384 struct dc_link *link, 1385 const struct link_training_settings *lt_settings) 1386 { 1387 /* aux timeout is already set to extended */ 1388 /* RESET/SET lttpr mode to enable non transparent mode */ 1389 uint8_t repeater_cnt; 1390 uint32_t aux_interval_address; 1391 uint8_t repeater_id; 1392 enum dc_status result = DC_ERROR_UNEXPECTED; 1393 uint8_t repeater_mode = DP_PHY_REPEATER_MODE_TRANSPARENT; 1394 1395 enum dp_link_encoding encoding = dp_get_link_encoding_format(<_settings->link_settings); 1396 1397 if (encoding == DP_8b_10b_ENCODING) { 1398 DC_LOG_HW_LINK_TRAINING("%s\n Set LTTPR to Transparent Mode\n", __func__); 1399 result = core_link_write_dpcd(link, 1400 DP_PHY_REPEATER_MODE, 1401 (uint8_t *)&repeater_mode, 1402 sizeof(repeater_mode)); 1403 1404 } 1405 1406 if (result == DC_OK) { 1407 link->dpcd_caps.lttpr_caps.mode = repeater_mode; 1408 } 1409 1410 if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT) { 1411 1412 DC_LOG_HW_LINK_TRAINING("%s\n Set LTTPR to Non Transparent Mode\n", __func__); 1413 1414 repeater_mode = DP_PHY_REPEATER_MODE_NON_TRANSPARENT; 1415 result = core_link_write_dpcd(link, 1416 DP_PHY_REPEATER_MODE, 1417 (uint8_t *)&repeater_mode, 1418 sizeof(repeater_mode)); 1419 1420 if (result == DC_OK) { 1421 link->dpcd_caps.lttpr_caps.mode = repeater_mode; 1422 } 1423 1424 if (encoding == DP_8b_10b_ENCODING) { 1425 repeater_cnt = dp_convert_to_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt); 1426 for (repeater_id = repeater_cnt; repeater_id > 0; repeater_id--) { 1427 aux_interval_address = DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER1 + 1428 ((DP_REPEATER_CONFIGURATION_AND_STATUS_SIZE) * (repeater_id - 1)); 1429 core_link_read_dpcd( 1430 link, 1431 aux_interval_address, 1432 (uint8_t *)&link->dpcd_caps.lttpr_caps.aux_rd_interval[repeater_id - 1], 1433 sizeof(link->dpcd_caps.lttpr_caps.aux_rd_interval[repeater_id - 1])); 1434 link->dpcd_caps.lttpr_caps.aux_rd_interval[repeater_id - 1] &= 0x7F; 1435 } 1436 } 1437 } 1438 1439 return result; 1440 } 1441 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org