reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/ath/ath.git/commit/?id=4ee62a717c5471caf9b50beb6eeefcf4ee0670a8
        git remote add ath https://git.kernel.org/pub/scm/linux/kernel/git/ath/ath.git
        git fetch --no-tags ath ath12k-split-phy
        git checkout 4ee62a717c5471caf9b50beb6eeefcf4ee0670a8
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash drivers/net/wireless/mediatek/mt76/