bypass 160 MHz limit in VGA adapters

[joevt]

I have a plugable USB-C to VGA adapter (2 lanes HBR2) which is capable of up to 330 MHz pixel clock but Apple's Intel graphics drivers have a limit of 160 MHz.

Below is a script to patch all Intel drivers. It sets the limit to 360 MHz. Tested IntelCFL in 10.14.6 and 10.15.2 and IntelSKL in 10.13.6.

Should probably change the perl command so that it tells you if the patch was successful.

#!/bin/sh

theoldhex=$(printf "%08x" 160000000)
theoldhex="\x${theoldhex:6:2}\x${theoldhex:4:2}\x${theoldhex:2:2}\x${theoldhex:0:2}"

thenewhex=$(printf "%08x" 360000000)
thenewhex="\x${thenewhex:6:2}\x${thenewhex:4:2}\x${thenewhex:2:2}\x${thenewhex:0:2}"

IFS=$'\n'
for thefile in $(find /System/Library/Extensions -name '*AppleIntel*Framebuffer'); do
	printf "Patching $thefile\n"
	#mv $thefile.bak $thefile.bak2
	sudo perl -i.bak -pe '$before = qr"(\x48\xc7\x85..\xff\xff)'${theoldhex}'"s;s/$before/$1'${thenewhex}'/g' $thefile
	printf "Re-signing $thefile\n"
	sudo codesign -f -s - $thefile
done
sudo touch /System/Library/Extensions