Hi Wentong, On Mon, Mar 27, 2023 at 02:23:05PM +0800, Wentong Wu wrote: > Intel Visual Sensing Controller (IVSC), codenamed "Clover Falls", is a > companion chip designed to provide secure and low power vision capability > to IA platforms. IVSC is available in existing commercial platforms from > multiple OEMs. > > The primary use case of IVSC is to bring in context awareness. IVSC > interfaces directly with the platform main camera sensor via a CSI-2 link > and processes the image data with the embedded AI engine. The detected > events are sent over I2C to ISH (Intel Sensor Hub) for additional data > fusion from multiple sensors. The fusion results are used to implement > advanced use cases like: > - Face detection to unlock screen > - Detect user presence to manage backlight setting or waking up system > > Since the Image Processing Unit(IPU) used on the host processor needs to > configure the CSI-2 link in normal camera usages, the CSI-2 link and > camera sensor can only be used in mutually-exclusive ways by host IPU and > IVSC. By default the IVSC owns the CSI-2 link and camera sensor. The IPU > driver can take ownership of the CSI-2 link and camera sensor using > interfaces exported via v4l2 sub-device. > > Switching ownership requires an interface with two different hardware > modules inside IVSC. The software interface to these modules is via Intel > MEI (The Intel Management Engine) commands. These two hardware modules > have two different MEI UUIDs to enumerate. These hardware modules are: > - ACE (Algorithm Context Engine): This module is for algorithm computing > when IVSC owns camera sensor. Also ACE module controls camera sensor's > ownership. This hardware module is used to set ownership of camera sensor. > - CSI (Camera Serial Interface): This module is used to route camera > sensor data either to IVSC or to host for IPU driver and application. > > IVSC also provides a privacy mode. When privacy mode is turned on, > camera sensor can't be used. This means that both ACE and host IPU can't > get image data. And when this mode is turned on, users are informed via > v4l2 control API. > > In summary, to acquire ownership of camera by IPU driver, first ACE > module needs to be informed of ownership and then to setup MIPI CSI-2 > link for the camera sensor and IPU. > > Implementation: > There are two different drivers to handle ACE and CSI hardware modules > inside IVSC. > - ivsc_csi: MEI client driver to send commands and receive notifications > from CSI module. > - ivsc_ace: MEI client driver to send commands and get status from ACE > module. > Interface is exposed via v4l2 sub-devcie APIs to acquire and release > camera sensor and CSI-2 link. Thanks for the update. Could you elaborate the decision of keeping the csi_bridge entirely separate from the cio2_bridge (to be turned to ipu_bridge first)? Both are doing essentially the same and using the same data structures, aren't they? -- Kind regards, Sakari Ailus
