[Bug 1958224] Re: brltty claiming cp210x devices on 22.04

[Steve Langasek]

I understand the importance of fixing this conflict, and I agree it's
bad behavior on the part of the hardware manufacturer that retail
devices were shipped using these generic USB IDs, but the consequence of
the proposed SRU - disabling the use of brltty on the USB ids in
question - is that a blind user who uses one of these devices, who has
successfully installed Ubuntu and has a working system, will on the
installation of this SRU have their only accessible tty device rendered
inoperable.

That represents a CRITICAL regression for the users in question.  It
effectively bricks their machine and requires the user to rely on a
sighted person (who is also Ubuntu-knowledgeable) to get it working
again.

So I am rejecting this SRU.  It's unfortunate that this wasn't caught
before release, but now that support for this hardware is present in the
release, we can't be bricking blind users' systems to enable other
cp210x devices.  We'll need to find some other path forward.

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Title:
  brltty claiming cp210x devices on 22.04

Status in brltty package in Ubuntu:
  Fix Committed
Status in brltty source package in Jammy:
  Confirmed

Bug description:
  * Impact

  The brltty udev rules are claiming generic devices IDs which makes
  some other devices like Arduino cards not able to interact with the
  serial port anymore

  * Test Case

  Try to use an Arduino over a cp210x or FTDI serial port, it should be
  able to talk to the computer

  * Regression potential

  There are some braille devices on the market using generic IDs which
  are going to stop working out of the box. Those devices are uncommon
  and it's arguably an hardware bugs they are using those IDs.

  -------------------

  Distributor ID:	Ubuntu
  Description:	Ubuntu Jammy Jellyfish (development branch)
  Release:	22.04
  Codename:	jammy
  brltty:  Installed: 6.4-2ubuntu1

   brltty appears once again to be claiming cp210x devices with the
  vendor/product ID of:

  idVendor=10c4, idProduct=ea60

  Example dmesg output:
    999.215968] usb 3-6.3: New USB device found, idVendor=10c4, idProduct=ea60, bcdDevice= 1.00
  [  999.215973] usb 3-6.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  [  999.215975] usb 3-6.3: Product: CP2103 USB to UART Bridge
  [  999.215977] usb 3-6.3: Manufacturer: Silicon Labs
  [  999.215978] usb 3-6.3: SerialNumber: 0005
  [  999.234070] usbcore: registered new interface driver usbserial_generic
  [  999.234081] usbserial: USB Serial support registered for generic
  [  999.235262] usbcore: registered new interface driver cp210x
  [  999.235272] usbserial: USB Serial support registered for cp210x
  [  999.235298] cp210x 3-6.3:1.0: cp210x converter detected
  [  999.237039] usb 3-6.3: cp210x converter now attached to ttyUSB0
  [  999.300049] input: PC Speaker as /devices/platform/pcspkr/input/input41
  [  999.807223] input: BRLTTY 6.4 Linux Screen Driver Keyboard as /devices/virtual/input/input42
  [  999.991926] usb 3-6.3: usbfs: interface 0 claimed by cp210x while 'brltty' sets config #1
  [  999.995045] cp210x ttyUSB0: cp210x converter now disconnected from ttyUSB0
  [  999.995066] cp210x 3-6.3:1.0: device disconnected

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