[Catalina] Dell 4021QW DP black screen issue

[krachbumms]

Hi,

Running Catalina 10.15.7 here and ran into a strange issue.
Just got my new Dell 4021QW, everything boots and works until after I login.
After the login the screen goes dark and the display detects no DP signal.
No comes the strange part, when I move the DP cable to the other DP port on the graphics card the monitor works again.
This switcheroo game works until the next boot, then I have to switch the cable to the other port again (and so on and on).

WhatEverGreen and lilu is the latest version, also tried VegaGraphicsFixup.kext.
Never had this problem with my Dell 3818DW screen.

Anybody else has this problem?

Markus

 

[Edhawk]

Not had the same problem, but something similar where one of my two Dell displays works and the other doesn't, both using DisplayPort connections.

Using the Dell Screen's controls I first switch inputs to HDMI or Mini DisplayPort, and then after the no signal message switch back again to DisplayPort. This fixes the issue so both screens work as expected.

This is a better option than physically unplugging and replugging the DP cable. As that is probably the easiest way to break a DP cable or damage one of the connectors on your Vega 56.

 

[krachbumms]

That workaround unfortunately doesn't work for me. Even with pulling the power plug on the monitor. The problem is the DP itself. It has to be changed from Port 1 to Port 2 on the graphics card (or vice versa at the next boot). Plugging it in at the same port again doesn't work.

 

[Middleman]

That workaround unfortunately doesn't work for me. Even with pulling the power plug on the monitor. The problem is the DP itself. It has to be changed from Port 1 to Port 2 on the graphics card (or vice versa at the next boot). Plugging it in at the same port again doesn't work.

Sounds like its switching because the display ports haven't been defined. Do you use a SSDT at all? One way to make the connection better and more permanent is to use a SSDT gpu spoof or device properties patch. For Vega56 there are a handful of device-id values you could use, like 687F for Radeon Vega 56.

Here's what you could do. When you boot in again, download Hackintools and select the Patch function. Check and make sure your ig-platform-id is correct before proceeding and then move to Connectors, select your DP ports and then go to 2nd patch tab. Under here you have a range of selections with which to patch your GPU. Basically what you want to do is apply a LSPCON patch to your DP ports and either set the port to auto-detect or pre-assign a connector value. There is also a hotplug reboot fix, which I suspect could be the problem you're encountering. Hackintools can patch whatever issue it is you're having with the GPU and put it into config.plist.

 

[krachbumms]

Sounds like its switching because the display ports haven't been defined. Do you use a SSDT at all? One way to make the connection better and more permanent is to use a SSDT gpu spoof or device properties patch. For Vega56 there are a handful of device-id values you could use, like 687F for Radeon Vega 56.

Here's what you could do. When you boot in again, download Hackintools and select the Patch function. Check and make sure your ig-platform-id is correct before proceeding and then move to Connectors, select your DP ports and then go to 2nd patch tab. Under here you have a range of selections with which to patch your GPU. Basically what you want to do is apply a LSPCON patch to your DP ports and either set the port to auto-detect or pre-assign a connector value. There is also a hotplug reboot fix, which I suspect could be the problem you're encountering. Hackintools can patch whatever issue it is you're having with the GPU and put it into config.plist.

@Middleman Thanks for the fast and thorough reply! Really appreciate it.

Tried to follow your explanation but it went a bit over my head. It pushed me in the right direction though. I use a SSDT for the Vega56 (SSDT-X299-Vega56.aml). After I removed that one everything started working.

Hackintool gives me funny values though for current framebuffer (under Patch):
- Intel Generation ???
- Plattform ID 0x0
- GPU Device ID 0x0
- GPU Name ???

 

[Middleman]

@Middleman Thanks for the fast and thorough reply! Really appreciate it.

Tried to follow your explanation but it went a bit over my head. It pushed me in the right direction though. I use a SSDT for the Vega56 (SSDT-X299-Vega56.aml). After I removed that one everything started working.

Hackintool gives me funny values though for current framebuffer (under Patch):
- Intel Generation ???
- Plattform ID 0x0
- GPU Device ID 0x0
- GPU Name ???

The values for the current framebuffer correspond to your CPUID1Data values. I assume you are using Skylake? Then you must select Skylake Desktop from the Patch selection menu at the bottom of the Hackintools NVRAM selection menu.

 

[Edhawk]

Your CPU doesn’t contain an IGPU, so the framebuffer settings in Hackintool are never going to show anything sensible.