iceprog leaves FTDI device in odd mode

[osresearch]

On the upduino v2 with ice40 up5k and an FTDI 232H chip, the device enumerates as a serial device and creates /dev/ttyUSB0. I can send/receive data from the board fine:

[1455866.817013] usb 1-1: new high-speed USB device number 90 using xhci_hcd
[1455866.957203] usb 1-1: New USB device found, idVendor=0403, idProduct=6014
[1455866.957211] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[1455866.957216] usb 1-1: Product: Single RS232-HS
[1455866.957220] usb 1-1: Manufacturer: FTDI
[1455866.958328] ftdi_sio 1-1:1.0: FTDI USB Serial Device converter detected
[1455866.958487] usb 1-1: Detected FT232H
[1455866.958846] usb 1-1: FTDI USB Serial Device converter now attached to ttyUSB0

When the board is reprogrammed with iceprog, however, it disconnects from /dev/ttyUSB0:

[1455919.013105] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
[1455919.013132] ftdi_sio 1-1:1.0: device disconnected

In order to have it re-enumerate and see the serial output from the FPGA, I have to unplug/re-plug the cable. Is there a way to have iceprog switch the FTDI back into serial mode after programming?

[osresearch]

As a workaround, I'm able to add this to my Makefile for forcing a reset, flashing the device, and then re-attaching the /dev/ttyUSB0 port to the FTDI SIO kernel driver:

%.flash: %.bin
        iceprog -e 128 # Force a reset to stop any serial output
        iceprog $<
        echo 1-1:1.0 > /sys/bus/usb/drivers/ftdi_sio/bind  # re-attach serial