kingo132
commented
3 years ago Append some useful information:
This machine's IODisplayAttributes lacks a lot of properties.
These properties seem to be set by framebuffer.
I tried to spoof the display productID, but doesn't change the brightness setting. So I guess it might be that the AMD driver encounter error in reading the brightness, so it thinks that the display cannot adjust the brightness, maybe it needs to tweak the AMD framebuffer driver
What I'm taking away from the display specs is that the internal display of this laptop is EDP. It looks like the 2020 iMac has an LVDS display.
Then again, I'd imagine that the brightness would be supported somehow. If it wasn't, there wouldn't even be a video signal in the first place.
I tried to spoof many different device-id with in navi10 family, all black screen.
Some information about LVDS and eDP
I don't know what AUX is, is it a headphone jack?? confused
But I found some boot error log about AMD and AUX, I don't know if it is related to the audio or backlight control
Only this post detailed about how to modify the connector information in AMD vBIOS, but it's too old to suit rx5700m: https://www.insanelymac.com/forum/topic/303186-how-to-modification-of-amd-fb-clover-injection/
as you can see, no slider at all
and digging deeper, there's only a few parameters under here, just like an external monitor which can not control brightness at all
from a normal Hackintosh which can adjust the brightness there are more parameters, such as bklt and brightness and so no
from the system log I can find this log when I open display preference
from dsdt and ssdt, I added some trace code into both the integrated gpu's LCD and discrete gpu's LCD, but they both never called at all, only _ADR method get called
Also from the boot log I noticed one line which is: AGDCBacklightControl: Didn't find DPMicro. But I couldn't find any information about this on the web.
I'm using SMBIOS iMac20,2, from what I researched these days, There are two prerequisites for the display slider to appear, one is display must built-in, and another is pnlf added and AppleBrightness get loaded. But I still can not get the slider. I am a bit at a loss now.