DDC/CI (ddccontrol) with Quadro P400


I have problems getting ddccontrol to work with Quadro P400 (tried both drivers 375 and 381).
Another machine with Quadro K420 works well - so it shouldn’t be ddccontrol’s fault.

The i2c devices are available in /dev, i2cdetect -l shows them, but when ddccontrol tries to access them, ioctl throws an IO error.

Is there no support for ddc/ci in the driver for P400 yet?
When will this be fixed?

Or does the P400 require a different procedure than previous devices?

Best regards