tree: https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-linus head: 9ebaef0540a981093bce5df15af32354d32391d9 commit: 265d1a90e4fb6d3264d8122fbd10760e5e733be6 [117/119] ALSA: usb-audio: scarlett2: Improve driver startup messages config: arc-allyesconfig (attached as .config) compiler: arceb-elf-gcc (GCC) 9.3.0 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 # https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/commit/?id=2... git remote add sound https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git git fetch --no-tags sound for-linus git checkout 265d1a90e4fb6d3264d8122fbd10760e5e733be6 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc

If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot lkp@intel.com

All warnings (new ones prefixed by >>):

...

sound/usb/mixer_scarlett_gen2.c:2000:5: warning: no previous prototype for 'snd_scarlett_gen2_controls_create' [-Wmissing-prototypes]

2000 | int snd_scarlett_gen2_controls_create(struct usb_mixer_interface *mixer, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/snd_scarlett_gen2_controls_create +2000 sound/usb/mixer_scarlett_gen2.c

1999

2000 int snd_scarlett_gen2_controls_create(struct usb_mixer_interface *mixer,

2001 const struct scarlett2_device_info *info) 2002 { 2003 int err; 2004 2005 /* Initialise private data, routing, sequence number */ 2006 err = scarlett2_init_private(mixer, info); 2007 if (err < 0) 2008 return err; 2009 2010 /* Read volume levels and controls from the interface */ 2011 err = scarlett2_read_configs(mixer); 2012 if (err < 0) 2013 return err; 2014 2015 /* Create the analogue output controls */ 2016 err = scarlett2_add_line_out_ctls(mixer); 2017 if (err < 0) 2018 return err; 2019 2020 /* Create the analogue input controls */ 2021 err = scarlett2_add_line_in_ctls(mixer); 2022 if (err < 0) 2023 return err; 2024 2025 /* Create the input, output, and mixer mux input selections */ 2026 err = scarlett2_add_mux_enums(mixer); 2027 if (err < 0) 2028 return err; 2029 2030 /* Create the matrix mixer controls */ 2031 err = scarlett2_add_mixer_ctls(mixer); 2032 if (err < 0) 2033 return err; 2034 2035 /* Create the level meter controls */ 2036 err = scarlett2_add_meter_ctl(mixer); 2037 if (err < 0) 2038 return err; 2039 2040 /* Set up the interrupt polling if there are hardware buttons */ 2041 if (info->button_count) { 2042 err = scarlett2_mixer_status_create(mixer); 2043 if (err < 0) 2044 return err; 2045 } 2046 2047 return 0; 2048 } 2049

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