[BRLTTY] [PATCH] don't steal abused USB ids

[Stanislav Brabec]

Dave Mielke wrote:
> [quoted lines by Stanislav Brabec on 2018/05/15 at 22:53 +0200]
> 
>> There is no need for such changes. You already have udev helper that starts 
>> the brltty daemon on demand. So there is no need to monitor devices. You can 
>> simply handle a single device passed by udev and quit when the device 
>> disappears. Now the device disappears, and the daemon still runs. When it 
>> re-appears, udev calls brltty_usb_run, but brltty also scans for the device 
>> (even if the udev rule is disabled).
> 
> no, it doesn't. That problem was fixed quite a while ago. Or are you using udev 
> without systemd?
> 
I cannot confirm that, at least for brltty-5.6 sitting on a bare CP2101
chip.

openSUSE Leap 15.0 still uses brltty-5.5, but openSUSE Tumbleweed
already upgraded to brltty-5.6. Both behaves in the same way. This is
systemd+udev based system.


Steps to reproduce:

0. Have a CP2101 device.

1. Disable all udev rules for 10c4/ea60 except brltty.

2. Connect CP2101 device.

Actual behavior: brltty sets config #1, which causes disappearing of
dev/ttyUSB0. (Probably expected.)

3. Disconnect CP2101 device.

4. Disable brltty udev rule for 10c4/ea60.

5. Connect CP2101 device.

Actual behavior: /dev/ttyUSB0 appears. After 4 seconds, brltty performs
a scan and sets config #1, which causes disappearing of /dev/ttyUSB0.

ps ax shows "brltty -E -n" permanently running on the system and
stealing all

Expected behavior: brltty handles only device passed by udev.

6. killall brltty

Actual behavior: /dev/ttyUSB0 appears and remains. (Correct.)

7. Run "brltty -E -n" from the command line (all CP2101 rules are still
disabled).

Actual behavior: /dev/ttyUSB0 appears. After 4 seconds, brltty performs
a scan and sets config #1, which causes disappearing of /dev/ttyUSB0.

Expected behavior: Do not scan for USB devices using hardcoded rules.

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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