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rockowitz
Second monitor connected over MST is not detected
Hi,
My graphic card is GeForce GTX 1050Ti and configuration is 2x Dell 2415U connected with DisplayPort using MST. Second monitor is not detected in ddcutil but shown and working in system.
ddcutil_detect.txt ddcutil_environment.txt
Please build from branch 1.0.2-dev, execute the following commands, and submit the output:
ddcutil detect --verbose
ddcutil environment --very-verbose
Also, please clarify how MST is being used. The 2415U does not support DisplayPort pass through, and there doesn't appear to be a docking station. Are you using DisplayPort MST hub such as this one from Monoprice?
Here are logs:
I must have looked in the wrong Dell manual before. Now I see that the monitor supports DisplayPort pass through.
The problem, I'm afraid, is in the Nvidia driver. There are 6 /dev/i2c devices. 0,1,2 are SMBus devices, while 3,4,5 are Nvidia devices. Only /dev/i2c-5 supports either EDID (on slave address x50) or DDC (on slave address x37), so ddcutil sees only 1 monitor. This is confirmed by the output of command i2cdetect, which the environment command executes through a command shell.
The environment output ends at the point it is trying to examine a huge /var/log/kern.log. Apparently it crashed. Were there any error messages that went to the terminal?
No errors occurred, it just executed for long time so I cancelled it. Here are logs with no cancellation from my side detect.txt environment.txt
Sorry to bump this old issue but I am in a very similar situation. I have 3 Dell U2415 plugged via MST to a NVIDIA GeForce RTX 2060 and I can only adjust brightness on the first screen in the chain. I am able to adjust the brightness on the three of them when on Windows with the Dell Display Manager tools which makes me think it is a software issue.
I'm afraid the answer is still the same: the Nvidia driver does not support DDC on MST devices.