Dell docking station video output (E7440)

[princerock]

Thanks Jake. Unfortunately I didn't see your message in time. I did some thing more "radical": I updated to High Sierra (well the old system is not all working anyway, so I guess I would just give another version a try). Again I followed your guide. During installation, the weird part is that I lost my internal display for a couple of times (laptop screen just went black). I thought the installation was dead but after I hooked up the HDMI cable I found the video output was on the external display only. That's quite strange but I managed to complete the install.

Then I unplugged the HDMI cable and tried the docking station. This time I used the DP port since I noticed your Clover config is already patching DP. Then.. for the first time, the external monitor received signal! It shows a "snowfall" for a couple of seconds (what you see on a old old analog TV without antenna). Then it shows the desktop. The resolution is correct, but the color is not :( It seems the black color has been changed to purple, and the whole screen feels like it's been covered with something. But, at least this is the first time I saw something through the docking station!

I then replaced the DP patch with DVI patch and tired the DVI cable. Restarted and the monitor's build-in speakers made some loud noise for a few seconds, and the picture came up. Unfortunately it's the same as the DP port. The color is still wrong.

Another problem I found is that with either DP or DVI port, I cannot shut down the laptop correctly. It just hangs there and I had to press and hold the power button to shut off.

All these problems make DVI/DP port unusable. So I had to switch back to HDMI. The problem is that with HDMI I always lose my internal display. SysPrefs->Display does not show it at all.

 

So I did more tests. One of those was that I completely disabled both patches for HDMI and DVI/DP. To my surprise, the external display still works through HDMI! IOreg shows the connector type is the default "0004 0000", yet my external monitor works fine.

 

Also with both patches disabled I got the internal display back - sort of. The first time I boot up, there is no internal display. But if I do a sleep and come back, I have both displays. Again, not sure why.

 

Finally I tried DVI/DP ports (without any patch), as expected, there is nothing at all showing up.

 

So to sum up (I know there is a lot of info, sorry about that), with High Sierra (10.13.6):

 

1. With HDMI and DVI/DP patches, I don't have internal display with HDMI connection; wrong color/no power off with DVI/DP;

 

2. Without any patches, HDMI still works and so does internal display after recovering from sleep.

 

3. In either option I never get the mirroring options" button in the menu bar.

 

Any insight on what is going on here? I'm more interested in #2 why internal display does not work on first boot but works after sleep. If this could be fixed, I think I can live without the docking station.

 

Thanks