Arch Linux

millus

Member

Registered: 2019-07-21

Posts: 244

External USB-C monitor doesn't get correctly recognized

I connect an ASUS ZenScreen external display that supports USB-C (with DisplayPort) to my archlinux notebook, but lsusb lists it wrongly as "billboard device" instead of monitor, so it is not usable:
"Bus 001 Device 005: ID 0bda:5450 Realtek Semiconductor Corp. BillBoard Device"
Any idea how to fix this?

progandy

Member

Registered: 2012-05-17

Posts: 5,317

Re: External USB-C monitor doesn't get correctly recognized

Does your usb-c port on the laptop support the DP-Altmode? Otherwise you can only use DisplayLink which is not that great and needs a proprietary driver that migh not work. https://wiki.archlinux.org/title/DisplayLink

Here is an explanation for the billboard stuff: http://www.technical-direct.com/en/typec_billboard/
You should get some information through lsusb in verbose mode:

lsusb -vd 0bda:5450

Last edited by progandy (2021-11-07 19:28:05)

---

| alias CUTF='LANG=en_XX.UTF-8@POSIX ' | alias ENGLISH='LANG=C.UTF-8 ' |

millus

Member

Registered: 2019-07-21

Posts: 244

Re: External USB-C monitor doesn't get correctly recognized

Oh hmm. I know it is Thunderbolt. But I now see it has the lightning symbol next to it, but not a "D" symbol.
So confusing how many USB-C "secrets" there are.

Edit:
Hrrrm I waited for 5 minutes now but the URL you posted is still loading in the browser, not yet showing anything (Chrome) o_o.

Last edited by millus (2021-11-07 19:35:00)

progandy

Member

Registered: 2012-05-17

Posts: 5,317

Re: External USB-C monitor doesn't get correctly recognized

Thunderbolt 3 should always have DP-AltMode. See my last edit to get some information from the billboard device.

---

| alias CUTF='LANG=en_XX.UTF-8@POSIX ' | alias ENGLISH='LANG=C.UTF-8 ' |

millus

Member

Registered: 2019-07-21

Posts: 244

Re: External USB-C monitor doesn't get correctly recognized

Thanks. I installed Opera from scratch and tried to open your URL there now, but it still won't load. Just swirling loading icon, blank page. oO All other web sites work as usual in both browsers..

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 75,979

Re: External USB-C monitor doesn't get correctly recognized

Webpage times out for me as well, possibly 503
Luckily there's always https://web.archive.org/web/20210905101 … billboard/

---

How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc

progandy

Member

Registered: 2012-05-17

Posts: 5,317

Re: External USB-C monitor doesn't get correctly recognized

Interesting, works for me. Anyways, verbose lsusb should spit out some billboard information about the negotiation status for alternate modes.

---

| alias CUTF='LANG=en_XX.UTF-8@POSIX ' | alias ENGLISH='LANG=C.UTF-8 ' |

millus

Member

Registered: 2019-07-21

Posts: 244

Re: External USB-C monitor doesn't get correctly recognized

lsusb

Bus 002 Device 004: ID 0bda:0412 Realtek Semiconductor Corp. 1-Port USB 3.1 Hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 8087:0a2b Intel Corp. Bluetooth wireless interface
Bus 001 Device 002: ID 0bda:58d1 Realtek Semiconductor Corp. USB2.0 HD UVC WebCam
Bus 001 Device 009: ID 0bda:5450 Realtek Semiconductor Corp. BillBoard Device
Bus 001 Device 008: ID 0bda:5412 Realtek Semiconductor Corp. 2-Port USB 2.1 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

lsusb -v

...
Bus 001 Device 009: ID 0bda:5450 Realtek Semiconductor Corp. BillBoard Device
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.01
  bDeviceClass           17 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x0bda Realtek Semiconductor Corp.
  idProduct          0x5450 
  bcdDevice            0.06
  iManufacturer          17 Realtek
  iProduct               18 BillBoard Device
  iSerial                19 123456789ABCDEFGH
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0012
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration         18 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass        17 
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 
      iInterface             18
...

Will look into the web site now, good idea @ archive.org..

Edit:
Well, it seems it basically says that my notebook's USB-C port doesn't support alternate/displaylink mode correctly so it ends up in billboard mode. :<

I wonder if an adapter for USB-C Thunderbolt -> HDMI -> USB-C would work...

Last edited by millus (2021-11-07 20:49:55)

progandy

Member

Registered: 2012-05-17

Posts: 5,317

Re: External USB-C monitor doesn't get correctly recognized

Since it is thunderbolt, maybe some you need to authorize the connection with e.g. boltctl or in sysfs: https://www.kernel.org/doc/html/v4.13/a … rbolt.html
or maybe there is a bios setting?

Last edited by progandy (2021-11-07 21:10:56)

---

| alias CUTF='LANG=en_XX.UTF-8@POSIX ' | alias ENGLISH='LANG=C.UTF-8 ' |

millus

Member

Registered: 2019-07-21

Posts: 244

Re: External USB-C monitor doesn't get correctly recognized

Thanks! Wow is this complicated -_- I feel like some system engineer..
Anyway I tried to look into " /sys/bus/thunderbolt..." mentioned on that kernel.org site, but I don't even have that folder on my system O_o. This looks like it could be a time sink of 30+ hours just to understand and figure out that these things just don't work (tm), lol..