Hi Stephen,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   c1ae3cfa0e89fa1a7ecc4c99031f5e9ae99d9201
commit: e2427b09ba929c2b9d02556b74a85161a7364792 phy: Add support for Qualcomm's USB HS phy
date:   5 weeks ago
config: i386-randconfig-x019-03061728 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        git checkout e2427b09ba929c2b9d02556b74a85161a7364792
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   drivers/built-in.o: In function `qcom_usb_hs_phy_power_off':
>> phy-qcom-usb-hs.c:(.text+0x1248): undefined reference to `extcon_unregister_notifier'
   drivers/built-in.o: In function `qcom_usb_hs_phy_power_on':
>> phy-qcom-usb-hs.c:(.text+0x1389): undefined reference to `extcon_get_state'
>> phy-qcom-usb-hs.c:(.text+0x13a4): undefined reference to `extcon_register_notifier'
   drivers/built-in.o: In function `qcom_usb_hs_phy_probe':
>> phy-qcom-usb-hs.c:(.text+0x1551): undefined reference to `extcon_get_edev_by_phandle'

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