On linux with udev, why are port whithout a parent filtered out of available_ports?

[dzamlo]

While playing with a Bluetooth serial port on Linux, I found out that the port was not listed by available_ports. I found out that the reason is that during the enumeration device without a parent are filtered out, and rfcomm (Bluetooth serial on Linux) device don't have a parent.

So my question is: Why it is the case ? Why are they filtered out?

Here is the relevant output from the libudev-rs list_devices example:

initialized: true
     devnum: Some(55296)
    syspath: Some("/sys/devices/virtual/tty/rfcomm0")
    devpath: Some("/devices/virtual/tty/rfcomm0")
  subsystem: Some("tty")
    sysname: Some("rfcomm0")
     sysnum: Some(0)
    devtype: None
     driver: None
    devnode: Some("/dev/rfcomm0")
     parent: None
  [properties]
    - "DEVNAME" "/dev/rfcomm0"
    - "DEVPATH" "/devices/virtual/tty/rfcomm0"
    - "MAJOR" "216"
    - "MINOR" "0"
    - "SUBSYSTEM" "tty"
  [attributes]
    - "address" Some("aa:aa:aa:aa:aa:aa")
    - "channel" Some("1")
    - "dev" Some("216:0")
    - "power/autosuspend_delay_ms" None
    - "power/control" Some("auto")
    - "power/runtime_active_time" Some("0")
    - "power/runtime_status" Some("unsupported")
    - "power/runtime_suspended_time" Some("0")
    - "subsystem" Some("tty")
    - "uevent" Some("MAJOR=216\nMINOR=0\nDEVNAME=rfcomm0")

[sirhcel]

Hello @dzamlo, I bet we are not excluding these ports on purpose or intent. According to the output above, they belong to the TTY subsystem which is scanned with libudev. Could you please open an issue for looking into this?

I'm thinking about adding some logging/tracing to the enumeration process for a while. May be the time is now.