Hello,
With the 4.1.5-1-ARCH #1 SMP PREEMPT Wed Aug 12 19:02:34 MDT 2015 armv7l GNU/Linux, my USB converters do not attach to /dev/ttyUSB*
$this->bbcode_second_pass_code('', '
[ 2305.091441] usb 1-1.3: Product: USB-Serial Controller
[ 2305.096673] usb 1-1.3: Manufacturer: Prolific Technology Inc.
[ 2394.070316] usb 1-1.3: USB disconnect, device number 8
[ 2396.094795] usb 1-1.5: new full-speed USB device number 9 using dwc_otg
[ 2396.217039] usb 1-1.5: New USB device found, idVendor=067b, idProduct=2303
[ 2396.224061] usb 1-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 2396.231583] usb 1-1.5: Product: USB-Serial Controller
[ 2396.236811] usb 1-1.5: Manufacturer: Prolific Technology Inc.
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It try both pl2303 and FTDI converter and linux-firmware is installed.
Thanks