Unleashing Responsiveness: A comprehensive approach to improve End-to-End latency for USB-C display for better UX
Ankit P. Navik, Sivakumar Thulasimani, Oren Novitzky · 2023
The COVID-19 pandemic has significantly accelerated the demand for multiple displays in the context of remote working and learning. One critical concern in laptop utilizing USB-C displays is their responsiveness. The link training establishes the physical link (4/2/1) and its parameters used for transmission of video and audio over the DP (Display Port) main link. The display driver, responsible for supporting various DP adapters, previously incorporated a static auxiliary retries during clock recovery, which impacted the detection of aux process. Additionally, the internal dependency of the display driver on resetting other enabled displays resulted in prolonged setup time for newly connected displays. Consequently, these factors contributed to increased End-to-End (E2E) latency for Type C displays operating in DP Alternate mode and USB4/ThunderboltTMTunnel mode. In this paper we present the approach to optimizing the E2E latency for type C display. We also present optimizations pursued and associated learnings for better user experience (UX). We show optimization results which measurably improves responsiveness.