[LinuxUser2393]

Hi,

I am desperate for some sort of brightness control! I read here

new feature for the DisplayLink DL-4xxx series available from DisplayLink driver release 8.1 Alpha as a preview. From the general release 8.1 M0, any user will be able to change brightness and contrast on USB monitors using any utility complying with the DDC/CI standard. This allows users to use a single application to change brightness and contrast on all their displays, either connected through any DisplayLink product, or to a standard computer graphics card.

Is there any chance for DDC/CI control with Linux? I've installed ddcutil

~$ sudo ddcutil usbenvironment
The following tests probe for USB connected monitors.

Checking for USB connected monitors...

   Using lsusb to summarize USB devices...
      Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
      Bus 001 Device 002: ID 8087:8008 Intel Corp. 
      Bus 001 Device 003: ID 0cf3:3004 Atheros Communications, Inc. AR3012 Bluetooth 4.0
      Bus 001 Device 004: ID 5986:055c Acer, Inc 
      Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
      Bus 002 Device 002: ID 8087:8000 Intel Corp. 
      Bus 002 Device 009: ID 1770:ff00  
      Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
      Bus 003 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver
      Bus 003 Device 006: ID 046d:c52b Logitech, Inc. Unifying Receiver
      Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
      Bus 004 Device 064: ID 17e9:ff03 DisplayLink 

   USB device toplogy...
      /:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 5000M
          |__ Port 2: Dev 64, If 0, Class=Vendor Specific Class, Driver=usbfs, 5000M
          |__ Port 2: Dev 64, If 1, Class=Application Specific Interface, Driver=, 5000M
      /:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/14p, 480M
          |__ Port 1: Dev 2, If 2, Class=Human Interface Device, Driver=usbhid, 12M
          |__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 12M
          |__ Port 1: Dev 2, If 1, Class=Human Interface Device, Driver=usbhid, 12M
          |__ Port 5: Dev 6, If 0, Class=Human Interface Device, Driver=usbhid, 12M
          |__ Port 5: Dev 6, If 1, Class=Human Interface Device, Driver=usbhid, 12M
          |__ Port 5: Dev 6, If 2, Class=Human Interface Device, Driver=usbhid, 12M
      /:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
          |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
              |__ Port 8: Dev 9, If 0, Class=Human Interface Device, Driver=usbhid, 12M
      /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
          |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
              |__ Port 3: Dev 3, If 0, Class=Wireless, Driver=, 12M
              |__ Port 3: Dev 3, If 1, Class=Wireless, Driver=, 12M
              |__ Port 4: Dev 4, If 1, Class=Video, Driver=uvcvideo, 480M
              |__ Port 4: Dev 4, If 0, Class=Video, Driver=uvcvideo, 480M

   Listing /dev/usb...
      total 0
      crw------- 1 root root 180, 0 Apr 17 12:46 hiddev0
      crw------- 1 root root 180, 1 Apr 18 16:49 hiddev1

   Listing /dev/hiddev*...
      ls: cannot access '/dev/hiddev*': No such file or directory

   Listing /dev/bus/usb...
      total 0
      drwxr-xr-x 2 root root 120 Apr 17 12:46 001
      drwxr-xr-x 2 root root 100 Apr 22 15:13 002
      drwxr-xr-x 2 root root 100 Apr 18 16:49 003
      drwxr-xr-x 2 root root  80 Apr 22 20:14 004

   Listing /dev/hidraw*...
      crw------- 1 root root 245, 0 Apr 17 12:46 /dev/hidraw0
      crw------- 1 root root 245, 1 Apr 17 12:46 /dev/hidraw1
      crw------- 1 root root 245, 2 Apr 18 16:49 /dev/hidraw2
      crw------- 1 root root 245, 3 Apr 18 16:49 /dev/hidraw3


Checking for USB HID devices using hiddev...
   Found 2 USB HID devices.

   Device /dev/usb/hiddev0, devnum.busnum: 3.2, vid:pid: 046d:c52b - Logitech USB Receiver
      Not a USB HID monitor

   Device /dev/usb/hiddev1, devnum.busnum: 3.6, vid:pid: 046d:c52b - Logitech USB Receiver
      Not a USB HID monitor

Checking for USB HID Report Descriptors in /sys/kernel/debug/hid...

~$ sudo ddcutil detect 
Invalid display
   I2C bus:             /dev/i2c-6
   Supports DDC:        false
   EDID synopsis:
      Mfg id:           CMN
      Model:            Unspecified
      Serial number:    Unspecified
      Manufacture year: 2012
      EDID version:     1.4
   DDC communication failed

No active displays found

There has got to be something I can do? I've had this monitor for what seems like a couple years and have been waiting to be able to use it at night. All of my other monitors have a much lower brightness and it's just not going to work to have something that leaves a view-burn in my retina every time I look at it..

I'm willing to beta test, debug, anything!!