FTDI usb to serial conflict with brltty

[Marty Vona]

Binary package hint: hal

I plugged in an FTDI usb to serial adaptor. I could see in syslog that it was detected and initially set up correctly as /dev/ttyUSB1, since this was the second usb to serial that I'd plugged into the machine at this point (the first has always worked fine). However, /dev/ttyUSB1 quickly disappeared, even though the device remained plugged in and I had taken no other action.

Eventually I found a report of a similar sounding issue at

http://dub.net.nz/hal

where it was stated that the problem arose due to a conflict with brltty, the braille tty subsystem, and that removing brltty (I'm not blind...) can solve it. I confirmed that fix does work in my case.

I don't have the syslog from my experience, but I'll reproduce here the syslog posted at the above URL:

Jun 8 11:15:10 localhost kernel: [ 322.884000] usb 2-1: new full speed USB device using uhci_hcd and address 5
Jun 8 11:15:11 localhost kernel: [ 323.076000] usb 2-1: configuration #1 chosen from 1 choice
Jun 8 11:15:11 localhost kernel: [ 323.080000] ftdi_sio 2-1:1.0: FTDI USB Serial Device converter detected
Jun 8 11:15:11 localhost kernel: [ 323.080000] drivers/usb/serial/ftdi_sio.c: Detected FT232BM
Jun 8 11:15:11 localhost kernel: [ 323.080000] usb 2-1: FTDI USB Serial Device converter now attached to ttyUSB0
Jun 8 11:15:11 localhost NetworkManager: ^I[1181258111.229590] nm_hal_device_added (): New device added (hal udi is '/org/freedesktop/Hal/devices/usb_device_403_6001_FTCXA3R6').
Jun 8 11:15:11 localhost NetworkManager: ^I[1181258111.252224] nm_hal_device_added (): New device added (hal udi is '/org/freedesktop/Hal/devices/usb_device_403_6001_FTCXA3R6_serial_usb_0').
Jun 8 11:15:11 localhost NetworkManager: ^I[1181258111.305511] nm_hal_device_added (): New device added (hal udi is '/org/freedesktop/Hal/devices/usb_device_403_6001_FTCXA3R6_if0').
Jun 8 11:15:11 localhost NetworkManager: ^I[1181258111.320061] nm_hal_device_added (): New device added (hal udi is '/org/freedesktop/Hal/devices/usb_device_403_6001_FTCXA3R6_usbraw').
Jun 8 11:15:14 localhost kernel: [ 326.460000] usb 2-1: usbfs: interface 0 claimed by ftdi_sio while 'brltty' sets config #1
Jun 8 11:15:14 localhost brltty[3542]: USB interface in use: ftdi_sio
Jun 8 11:15:14 localhost kernel: [ 326.460000] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
Jun 8 11:15:14 localhost kernel: [ 326.460000] ftdi_sio 2-1:1.0: device disconnected
Jun 8 11:15:14 localhost NetworkManager: ^I[1181258114.611105] nm_hal_device_removed (): Device removed (hal udi is '/org/freedesktop/Hal/devices/usb_device_403_6001_FTCXA3R6_serial_usb_0').

[sglow (sag-ollies)]

I had the same problem. The solution is very simple:

sudo apt-get remove brltty

[Marty Vona (vona)]

Yup. As I said, I did confirm that removing brltty appears to work around the issue. I am reporting the bug because this truly is a problem, even though there is a workaround -- you should not have to remove a standard and obscure part of a default install just to get a usb to serial adaptor working. What are you supposed to do if you actually need to use brltty? And it did not appear that this issue was documented in launchpad yet.

[Mathieu Trudel-Lapierre (cyphermox)]

I also did notice the issue on my work machine. Does it make sense to keep brltty as the default for all installs? I can understand that keeping it there does make it easier for blind people to use the system right from the start, without having to figure out how to install the package that is missing for them to see what they want to type, etc... It is after al easier to remove the package when you don't need it than to add it, when it provides functionality that you'd need to do the operation ;)

If the idea really is that you need a serial dongle to connect a braille tty system, I guess there could be some type of notification from HAL, maybe, to ask whether the user wants to remove brltty the first time a serial dongle is connected, in case the user doesn't need the brltty and would like to use their usb-serial connector in another way.

[kenny (mramage+ubuntu-com)]

This is really a bug in the BRLTTY package. It incorrectly identifies the FTDI USB to serial adapter as a braille device, just because a manufacturer of braille devices used this particular chip to add a USB connection to their braille device. This particular chip is very common in many devices (especially in the embedded systems world). Since the BRLTTY package takes full control over any device it decides is a braille device, it breaks many innocent other devices. This should be fixed either in BRLTTY, or BRLTTY should not be a default package.

One way to enable braille devices from system setup to everyday use is to allow it to take control of the FTDI devices during installation, then ask if the user uses braille devices. If they answer yes, then install BRLTTY, if not then do not install it. This would allow it to work as it currently does for those who do need it, but doesn't break the many other devices that also use the FTDI chip.

[xteejx (xteejx-deactivatedaccount)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue that you reported is one that should be reproducible with the live environment of the Desktop CD of the current release - Karmic Koala. It would help us greatly if you could test with it so we can work on getting it fixed in Ubuntu. Thanks again and we appreciate your help.

[Marty Vona (vona)]

I just tested this on 9.10, and was not able to reproduce. The test machine did not have brltty removed (it still appears to be installed by default). I hotplugged two usb to serial devices. The first was not an FTDI, but the second was. Both /dev/ttyUSB0 and /dev/ttyUSB1 appeared and persisted as expected.

[xteejx (xteejx-deactivatedaccount)]

This bug report is being closed due to your last comment regarding this being fixed with an update. For future reference you can manage the status of your own bugs by clicking on the current status in the yellow line and then choosing a new status in the revealed drop down box. You can learn more about bug statuses at https://wiki.ubuntu.com/Bugs/Status. Thank you again for taking the time to report this bug and helping to make Ubuntu better. Please submit any future bugs you may find.