Graphics pipeline token synchronization

Abstract

A graphics system including a custom graphics and audio processor produces exciting 2D and 3D graphics and surround sound. The system includes a graphics and audio processor including a 3D graphics pipeline and an audio digital signal processor. The graphics pipeline processes graphics commands at different rates depending upon the type of operation being performed. This makes it difficult to synchronize pipeline operations with external operations (e.g., a graphics processor with a main processor). To solve this problem, a synchronization token including a programmable data message is inserted into a graphics command stream sent to a graphics pipeline. At a predetermined point near the bottom of the pipeline, the token is captured and a signal is generated indicated the token has arrived. The graphics command producer can look at the captured token to determine which of multiple possible tokens has been captured, and can use the information to synchronize a task with the graphics pipeline. Applications include maintaining memory coherence in memory shared between the 3D graphics pipeline and a graphics command producer.