The Display Subsystem (DSS) is a flexible, multi-pipeline subsystem that supports high-resolution display outputs. DSS includes input pipelines providing multi-layer blending with transparency to enable on-the-fly composition. Various pixel processing capabilities are supported, such as color space conversion and scaling, among others. DSS includes a DMA engine, which allows direct access to the frame buffer (device system memory).

Display outputs can connect seamlessly to an Open LVDS Display Interface transmitter (OLDITX), or can directly drive device pads as a Display Parallel Interface (DPI).This document has detailed API description that user can use to make use of the DSS driver.

DSS supports two types of display interfaces:

Display parallel interface via DISPC Video Port 2 (VP2) output.
Two low-voltage differential signaling (LVDS) interfaces, each with four data lanes and one clock lane, via Open LDI Transmitters (OLDITX0 and OLDITX1) connected to DISPC Video Port 1 (VP1) output.

DSS BLOCK DIAGRAM

Features Supported

Support for Video Pipleline configuration for VID and VIDL.
Support configuration for Video port configuration for VP1.
Support configuration for single link and dual link OLDI panel on VP1.
Support for ARGB8888, BGRA8888, RGBA8888, RGB24 and BGR frame formats for video pipeline input.
Support for video port timing parameters configuration.
Support configuration display plane zorder for Overlay manager OVR1.
Support for scaling on VID video pipeline.
Support for background color programming for Overlay manager OVR1.
Support for colorbar test pattern generation from OVR1.
Alpha blending support: embedded pixel alpha (ARGB and RGBA), global pixel, combination of global pixel and pixel alpha.
Support for display sharing with HLOS with VIDL pipeline, OVR1 and VP1 in control of MCU and zorder configuration controlled by MCU.

Safety Features:

Support for 4 programmable (position/size) safety check regions on each display output.
Support for 1 safety check region on each input video pipeline output.
Support for MISR (Multiple Input Signature Register) on each safety region, used to perform data correctness check and/or freeze frame detection.