Monitor on HP Thunderbolt Dock G2 not being detected

[FoxBuru]

Hello!

I'm having issues trying to control brightness and contrast on a Sceptre monitor connected to any of the DisplayPorts of an HP Thunderbolt Dock G2. Brightness control works properly on Windows, even when the mechanism is kind of choppy from time to time (but I think that's due to a problem on the monitor rather than the dock being icky). There's a caveat: As long as I connect a monitor on the single Thunderbolt-capable port of the dock, I'm able to talk DDC/CI to the monitor connected there, but not to any of the ones connected either to the DisplayPort ports, or the USB-C DP Alt Mode capable port (But I assume that's possible due to the way the video signal is reaching the GPU, connected directly from a Thunderbolt source, rather than passing over the DisplayPort IC hub on the dock).

I'm sending two interrogations (one with a single monitor connected via the USB-C DP alt capable port, and the other one with one monitor on the USB-C DP port, and another monitor on the Thunderbolt-capable port).

Thanks in advance!

user_interrogation.log
user_interrogation_thunderbolt_and_dp.log

[rockowitz]

Docking stations are problematic. Whether they properly transmit DDC messages on the I²C bus seems to be a matter of hardware/driver interaction. See issue #400 with an example of a HP dock not properly working with the amdgpu driver.