Enables up to four-channel UHBR13.5 link rate support (up to 54 Gbps throughput) 
The Display Port 2.1a update effectively doubles the length of passive cables for UHBR13.5 GPU-to-monitor connectivity, which was previously only supported via DP80 UHBR cables, providing greater flexibility for consumer gaming or workstation setups.
It released a new Automotive Extended Services Protocol specification for Display Port 2.1a and the latest version of the VESA Embedded Display Port (eDP) specification, version 1.5a. 
With the Display Port 2.1a update, the new DP54 cable specification supports UHBR10 and UHBR13.5 receivers and source devices with passive cable lengths up to two meters. UHBR13.5-enabled displays can drive resolution/refresh rate combinations up to 8K 2K (240Hz) or 8K 4K (120Hz) on four channels.