I' upgrading from my old HTPC (Xtreamer Ultra2) with a Geforce GT 520M graphics to a HTPC with an Athlon 200GE VEGA GPU.
I'm running the latest LE 9.2.2.
The HTPC is connected to an older AV receiver and from the receiver to an older FullHD TV via HDMI.
I had to solve two problems with my old HTPC:
1) the TV doesn't send a proper EDID, the EDID is missing 24Hz and 23.976Hz refresh rates
2) If the receiver was not on or it was switched to another input when powering on the HTPC, the HTPC started in some unsupported (by the TV) resolution (1024x768 I think)
I was able to solve both problems by this xorg.conf:
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor"
VendorName "Samsung"
ModelName "PS50A557"
HorizSync 26.0 - 76.0
VertRefresh 23.0 - 61.0
# 1920x1080p @ 50Hz (EIA/CEA-861B)
ModeLine "1920x1080_50" 148.500 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync
# 1920x1080p @ 60Hz (EIA/CEA-861B)
ModeLine "1920x1080_60" 148.500 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
# 1920x1080p @ 24Hz (EIA/CEA-861B)
ModeLine "1920x1080_24" 74.250 1920 2558 2602 2750 1080 1084 1089 1125 +hsync +vsync
# 1920x1080p @ 23.976Hz (EIA/CEA-861B)
# ModeLine "1920x1080_23.976" 74.175 1920 2558 2602 2750 1080 1084 1089 1125 +hsync +vsync
# 1920x1080p @ 23.976Hz
ModeLine "1920x1080_23.976" 74.230 1920 2560 2604 2752 1080 1084 1089 1125 +hsync +vsync
# 1920x1080i @ 50Hz (EIA/CEA-861B)
Modeline "1920x1080_50i" 74.250 1920 2448 2492 2640 1080 1085 1095 1125 +hsync +vsync Interlace
# 1920x1080i @ 60Hz (EIA/CEA-861B)
Modeline "1920x1080_60i" 74.250 1920 2008 2052 2200 1080 1085 1095 1125 +hsync +vsync interlace
# 1920x1080p @ 59.94Hz (EIA/CEA-861B)
ModeLine "1920x1080_59.94" 148.350 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
# 1920x1080i @ 59.94Hz (EIA/CEA-861B)
Modeline "1920x1080_59.94i" 74.175 1920 2008 2052 2200 1080 1085 1095 1125 +hsync +vsync Interlace
# 1920x1080p @ 25Hz (EIA/CEA-861B)
ModeLine "1920x1080_25" 74.250 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync
# 1920x1080p @ 29.97Hz (EIA/CEA-861B)
ModeLine "1920x1080_29.97" 74.175 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
# 1920x1080p @ 30Hz (EIA/CEA-861B)
ModeLine "1920x1080_30" 74.250 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
Option "ExactModeTimingsDVI" "True"
Option "UseEDIDFreqs" "FALSE"
Option "UseEDIDDpi" "FALSE"
Option "ModeValidation" "NoEdidModes"
Option "DPMS"
EndSection
Section "Device"
Identifier "nvidia"
Driver "nvidia"
Option "NoLogo" "true"
Option "DynamicTwinView" "false"
Option "NoFlip" "false"
Option "FlatPanelProperties" "Scaling = Native"
Option "ModeValidation" "NoVesaModes, NoXServerModes, NoVertRefreshCheck, NoHorizSyncCheck"
Option "UseDisplayDevice" "DFP-0"
Option "ConnectedMonitor" "DFP-0"
Option "CustomEDID" "DFP-0:/storage/.config/edid.bin"
Option "ModeDebug" "false"
Option "HWCursor" "false"
EndSection
Section "Screen"
Identifier "screen"
Device "nvidia"
Monitor "Monitor"
# Option "ColorRange" "Full"
# Option "ColorRange" "Limited"
# Option "ColorSpace" "RGB"
# Option "ColorSpace" "YCbCr444"
SubSection "Display"
Modes "1920x1080_23.976" "1920x1080_60" "1920x1080_50" "1920x1080_24" "1920x1080_50i" "1920x1080_60i" "1920x1080_59.94" "1920x1080_59.94i"
EndSubSection
EndSection And I was so naive, that I thought that simply changing the driver from nvidia to amdgpu will work 
It didn't ...
The problem probably is, that the amdgpu doesn't support the needed options.
Any ideas how to solve this with the new GPU