DisplayPort Secondary Data Packets for Power Management
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Solution Overview
Problem
Current techniques for regulating power consumption in computer systems, particularly in multimedia operations, are inadequate in efficiently managing power usage during periods of inactivity, leading to unnecessary energy wastage.
Innovation Solution
A system that includes a software driver to determine when to power down or power up components of a graphics subsystem and display device based on system activity, using a timing controller to enter self-refresh display mode and transmit secondary data packets over a DisplayPort interface, allowing for reduced power consumption by capturing and repeatedly displaying images when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power consumption is regulated by powering down graphics processing devices during inactivity, then energy efficiency is improved, but the system responds slower when graphics processing activity is detected
Solution Approach 1:
The system performs preliminary actions by capturing and storing a current image before entering self-refresh mode. When graphics processing activity is detected, the stored image is immediately displayed while the graphics processing device powers up, eliminating the delay that would otherwise occur while waiting for the first frame to be rendered. This preliminary capture of the image state allows the system to maintain visual continuity during power transitions.
2Use of energy by moving object
If the timing controller repeatedly displays a captured image in self-refresh mode, then power consumption is reduced, but image quality or display fidelity may be compromised
Solution Approach 1:
The timing controller implements periodic action by repeatedly displaying the captured image at the refresh rate during self-refresh mode. This periodic display maintains the display's operational state and timing synchronization while consuming significantly less power than continuous active rendering. The captured image is held in the display buffer and refreshed periodically to maintain visibility and readiness for upcoming graphics content.
3Extent of automation
If secondary data packets are transmitted over DisplayPort to control target device, then power management control is improved, but communication protocol complexity increases
Solution Approach 1:
The secondary data packets transmitted over the DisplayPort interface serve multiple functions: they convey power management commands from the host system to the target device, acknowledge receipt of commands, and coordinate the timing of power state transitions. This multi-functional use of a single communication mechanism eliminates the need for separate dedicated control channels, reducing overall system complexity while maintaining comprehensive power management capability.
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
Techniques are described to transmit commands to a display device. The commands can be transmitted in header byte fields of secondary data packets. The commands can be used to cause a target device to capture a frame, enter or exit self refresh mode, or reduce power use of a connection. In addition, a request to exit main link standby mode can cause the target enter training mode without explicit command to exit main link standby mode.