I have followed this document:
in FW R14.1, we can use the following commands to disable the modem port:
echo 0 > /sys/class/android_usb/android0/enable
echo diag,rmnet,ecm > /sys/class/android_usb/android0/functions
echo 1 > /sys/class/android_usb/android0/enable
But in FW R15.1, there is no such function in /sys/class/android_usb/android0/
You might need to refer to this:
FYI, my test shows that it is possible to remove modem port in Windows by the following command on WP7702 FW 15.1:
echo "" > /sys/kernel/config/usb_gadget/g1/UDC
mkdir /sys/kernel/config/usb_gadget/g2/
mkdir /sys/kernel/config/usb_gadget/g2/configs/c.1/
mkdir /sys/kernel/config/usb_gadget/g2/functions/diag.diag
ln -s /sys/kernel/config/usb_gadget/g2/functions/diag.diag /sys/kernel/config/usb_gadget/g2/configs/c.1/
mkdir /sys/kernel/config/usb_gadget/g2/functions/ecm.usb0
ln -s /sys/kernel/config/usb_gadget/g2/functions/ecm.usb0 /sys/kernel/config/usb_gadget/g2/configs/c.1
mkdir /sys/kernel/config/usb_gadget/g2/functions/rmnet_bam.rmnet_bam_dmux
ln -s /sys/kernel/config/usb_gadget/g2/functions/rmnet_bam.rmnet_bam_dmux /sys/kernel/config/usb_gadget/g2/configs/c.1
chmod 777 -R /sys/kernel/config/usb_gadget/g2/bDeviceClass /sys/kernel/config/usb_gadget/g2/bDeviceProtocol /sys/kernel/config/usb_gadget/g2/bDeviceSubClass /sys/kernel/config/usb_gadget/g2/bMaxPacketSize0 /sys/kernel/config/usb_gadget/g2/bcdDevice /sys/kernel/config/usb_gadget/g2/bcdUSB /sys/kernel/config /usb_gadget/g2/idProduct /sys/kernel/config/usb_gadget/g2/idVendor
cat /sys/kernel/config/usb_gadget/g1/bDeviceClass > /sys/kernel/config/usb_gadget/g2/bDeviceClass
cat /sys/kernel/config/usb_gadget/g1/bDeviceProtocol > /sys/kernel/config/usb_gadget/g2/bDeviceProtocol
cat /sys/kernel/config/usb_gadget/g1/bDeviceSubClass > /sys/kernel/config/usb_gadget/g2/bDeviceSubClass
cat /sys/kernel/config/usb_gadget/g1/bMaxPacketSize0 > /sys/kernel/config/usb_gadget/g2/bMaxPacketSize0
cat /sys/kernel/config/usb_gadget/g1/bcdDevice > /sys/kernel/config/usb_gadget/g2/bcdDevice
cat /sys/kernel/config/usb_gadget/g1/bcdUSB > /sys/kernel/config/usb_gadget/g2/bcdUSB
cat /sys/kernel/config/usb_gadget/g1/idProduct > /sys/kernel/config/usb_gadget/g2/idProduct
cat /sys/kernel/config/usb_gadget/g1/idVendor > /sys/kernel/config/usb_gadget/g2/idVendor
echo "msm_hsusb" > /sys/kernel/config/usb_gadget/g2/UDC