先附上Freescale的IPU功能概述與使用原則：
The goal of the IPU is to provide comprehensive support for the flow of data from an image sensor and/or to a display device. This support covers all aspects of these activities:
• Connectivity to relevant devices - cameras, displays, graphics accelerators, TV encoders and decoders.
• Related image processing and manipulation: sensor image signal processing, display processing, image conversions, etc.
• Synchronization and control capabilities (to avoid tearing artifacts). This integrative approach leads to several significant advantages:
• Automation: The involvement of the ARM platform in image management is minimized. In particular, display refresh/update and a camera preview (displaying the input from an image sensor) can be performed completely autonomously. The resulting benefits are reducing the overhead due to SW-HW synchronization, freeing the ARM platform to perform other tasks and reduced power consumption (when the ARM core is idle and can be powered down).
• Optimal data path: Access to system memory is minimized. In particular, significant processing can be performed on-the-fly while receiving data from an image sensor and/or sending data to a display. System memory is used essentially only when a change in pixel order or frame rate is needed. The resulting benefits are reduced load on the system bus and further reduction of power consumption.
• Resource sharing: Maximal HW reuse for different applications, resulting with the support of a wide range of requirements with minimal HW.
The HW reuse mentioned above is enabled by a sophisticated configurability of each HW block. This configurability also allows the support of a wide range of external devices, data formats and operation modes. The resulting flexibility is important also because the support requirements are evolving significantly, so expected future changes need to be anticipated and accounted for. The following further principles guided the choice of support provided by the IPU:
• For key applications that DESERVE and NEED HW support (for acceleration or low power), provide the best support (leading to an optimal implementation).
• For additional applications that can benefit from the HW, consider cost vs. benefit of making minor modifications/extensions to support them.
• For all other relevant applications (to be supported by SW), verify that their support is not degraded.
• Whenever possible, let the operating system (and its windowing system) act as it would without the IPU.
首先看看iMX53整體系統框圖，看看IPU位於整個SOC系統中的位置和與之相關聯模塊的架構關係。
iMX53系統框架圖
從框圖佈局看，Freescale架構人員將IPU置於ARM框架之上，可見他們對IPU模塊的鐘愛程度，或者是因爲IPU是自己搞的而ARM只是一個外來的IP？
從此圖可知IPU掛接在了AXI與AHB總線上，通過總線他可與以下模塊產生數據交互：ARM控制核心
RAM（DDR3）
GPU2D
GPU3D
VPU
除此之外IPU還有2個Camera接口，通過LDB到LVDS屏，直接控制LCD1、LCD2，通過TV-Encoder到VGA或HD TV/OUT接口。
