Resolution hack.txt

Resolution hack:

productID: 0x3047 = 12359 dec
vendorID: 0x4ca3 = 19619 dec

To do this, you have to create an override based on your DisplayVendorID and DisplayProductID.
In Terminal run this command:
ioreg -lw0 | grep IODisplayPrefsKey

It will output something like this:
"IODisplayPrefsKey" = "IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@0/display0/AppleBacklightDisplay-30e4-2d8"

At the end of the string you will see some hex values, in this case 0x30e4 and 0x2db.
Your DisplayVendorID is 0x30e4 and your DisplayProductID is 0x2db.

Create an Override folder named DisplayVendorID-30e4 by entering:
sudo mkdir /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-30e4

Next create a Display Override file by entering:
sudo vi /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-30e4/DisplayProductID-2db

In this file, paste this code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>DisplayProductName</key>
        <string>Lenovo x220 Display</string>
        <key>DisplayProductID</key>
        <integer>728</integer>
        <key>DisplayVendorID</key>
        <integer>12516</integer>
        <key>scale-resolutions</key>
        <array>
                <data>AAAGAAAAA2A=</data>
                <data>AAAHgAAABDg=</data>
        </array>
</dict>
</plist>