[alsa-devel] [PATCH v2 -next] soundwire: Fix -Wunused-function warning

[kbuild test robot]

Hi YueHaibing,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20190823]

url:    https://github.com/0day-ci/linux/commits/YueHaibing/soundwire-Fix-Wunused-function-warning/20190825-083159
config: x86_64-randconfig-g004-201934 (attached as .config)
compiler: gcc-7 (Debian 7.4.0-10) 7.4.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp at intel.com>

All errors (new ones prefixed by >>):

>> ERROR: "sdw_acpi_find_slaves" [drivers/soundwire/soundwire-bus.ko] undefined!
   WARNING: "ftrace_set_clr_event" [vmlinux] is a static EXPORT_SYMBOL_GPL

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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