Raspberry Pi with Arduino Nano USB serial gateway

[ToniA]

I'm trying to use Arduino Nano as serial gateway on RPi 2, but I'm stuck with the Nano not being detected when Raspberry boots up. To make it weirder, it works fine if I plug the Nano in when the RPi is already running... A Duemilanove board works fine, but I was hoping for something smaller.

Does anybody have any idea what's wrong with this setup?

Duemilanove is detected fine on boot (dmesg):

[    3.864401] usb 1-1.2: new full-speed USB device number 4 using dwc_otg
...
[    4.013350] usb 1-1.2: New USB device found, idVendor=0403, idProduct=6001
[    4.013363] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    4.013372] usb 1-1.2: Product: FT232R USB UART
[    4.013381] usb 1-1.2: Manufacturer: FTDI
[    4.013389] usb 1-1.2: SerialNumber: A101KWLO

... but the Nano isn't:

[    4.115330] usb 1-1.4: new full-speed USB device number 5 using dwc_otg
...
[    4.205056] usb 1-1.4: device descriptor read/64, error -32
...
[    4.401434] usb 1-1.4: device descriptor read/64, error -32

Also 'lsusb' doesn't show it.

But if I plug it in into a running RPi, it works just fine, until it's again lost on the next reboot:

[  122.544930] usb 1-1.4: new full-speed USB device number 10 using dwc_otg
[  122.673685] usb 1-1.4: New USB device found, idVendor=0403, idProduct=6001
[  122.673714] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  122.673731] usb 1-1.4: Product: FT232R USB UART
[  122.673746] usb 1-1.4: Manufacturer: FTDI
[  122.673761] usb 1-1.4: SerialNumber: AL01GVNR
[  122.682518] ftdi_sio 1-1.4:1.0: FTDI USB Serial Device converter detected
[  122.682797] usb 1-1.4: Detected FT232RL
[  122.683895] usb 1-1.4: FTDI USB Serial Device converter now attached to ttyUSB1

[ToniA]

Hmm. I'm going to try this: https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=59420

Seems like I need to solder the pins 25 & 26 together on the USB chip of the Nano. Now my Duemilanove is failing to connect on boot as well...