Hi Daniel, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on tiwai-sound/for-next] [also build test WARNING on v5.18-rc4 next-20220422] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/intel-lab-lkp/linux/commits/Daniel-Kaehn/Add-generic-serial-MIDI-driver-using-serial-bus-API/20220421-035024 base: https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-next config: arm64-allyesconfig (https://download.01.org/0day-ci/archive/20220426/202204260120.TIXTqkq1-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 1cddcfdc3c683b393df1a5c9063252eb60e52818) 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/intel-lab-lkp/linux/commit/65e00db0913a4019c3158e31aa6b2fd2c28ba03f git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Daniel-Kaehn/Add-generic-serial-MIDI-driver-using-serial-bus-API/20220421-035024 git checkout 65e00db0913a4019c3158e31aa6b2fd2c28ba03f # 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 arch/arm64/kernel/ drivers/acpi/arm64/ sound/drivers/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): >> sound/drivers/serial-generic.c:192:6: warning: no previous prototype for function 'snd_serial_generic_write_wakeup' [-Wmissing-prototypes] void snd_serial_generic_write_wakeup(struct serdev_device *serdev) ^ sound/drivers/serial-generic.c:192:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void snd_serial_generic_write_wakeup(struct serdev_device *serdev) ^ static 1 warning generated. vim +/snd_serial_generic_write_wakeup +192 sound/drivers/serial-generic.c 191 > 192 void snd_serial_generic_write_wakeup(struct serdev_device *serdev) 193 { 194 struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev); 195 196 if (!snd_rawmidi_transmit_empty(drvdata->midi_output)) 197 snd_serial_generic_output_write(drvdata->midi_output); 198 } 199 -- 0-DAY CI Kernel Test Service https://01.org/lkp