Re: [PATCH v2 0/3] media: pci: intel: ivsc: Add driver of Intel Visual Sensing Controller(IVSC)

From: Laurent Pinchart
Date: Wed Feb 15 2023 - 04:44:26 EST

Hello Wentong,

On Mon, Feb 13, 2023 at 10:23:44AM +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

Do you have plan to support these features in the ivsc driver in the
future ?

> 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 provided by this IVSC driver.
>
> 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, host IPU driver is
> informed via a registered callback, so that user can be notified.

How does the privacy mode work, and how can the user trust that the
closed-source IVSC and IME firmwares will honour the privacy settings ?

> 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.
> - mei_csi: MEI client driver to send commands and receive notifications
> from CSI module.
> - mei_ace: MEI client driver to send commands and get status from ACE
> module.
> Interface is exposed via ivsc.h to acquire and release camera sensor and
> CSI-2 link.

Do I understand correctly, from your diagram below, that the
communication between the IME and IVSC goes through SPI ?

> Below diagram shows connections of IVSC/ISH/IPU/Camera sensor.
> -----------------------------------------------------------------------------
> | Host Processor |
> | |
> | ----------------- ----------------- --------------- |
> | | | | | | | I2C |
> | | IPU | | ISH | |camera driver|--| |
> | | | | | | | | |
> | ----------------- ----------------- --------------- | |
> | | | | | |
> | | | --------------- | |
> | | | | | | |
> | | | | IVSC driver | | |
> | | | | | | |
> | | | --------------- | |
> | | | | | |
> ----------------|-----------------------|----------------------|---------|---
> | CSI | I2C |SPI |
> | | | |
> ----------------|-----------------------|---------------- | |
> | IVSC | | | |
> | | | | |
> | ----------------- ----------------- | | |
> | | | | | | | |
> | | CSI | | ACE | |------| |
> | | | | | | |
> | ----------------- ----------------- | |
> | | | I2C | |
> ----------------|-----------------------|---------------- |
> | CSI | |
> | | |
> -------------------------------- |
> | | I2C |
> | camera sensor |-----------------------------|
> | |
> --------------------------------
>
> Wentong Wu (3):
> media: pci: intel: ivsc: Add CSI submodule
> media: pci: intel: ivsc: Add ACE submodule
> media: pci: intel: ivsc: Add acquire/release API for ivsc
>
> drivers/media/pci/Kconfig | 1 +
> drivers/media/pci/intel/Makefile | 2 +
> drivers/media/pci/intel/ivsc/Kconfig | 12 +
> drivers/media/pci/intel/ivsc/Makefile | 7 +
> drivers/media/pci/intel/ivsc/ivsc.c | 84 +++++
> drivers/media/pci/intel/ivsc/mei_ace.c | 472 +++++++++++++++++++++++++
> drivers/media/pci/intel/ivsc/mei_ace.h | 36 ++
> drivers/media/pci/intel/ivsc/mei_csi.c | 342 ++++++++++++++++++
> drivers/media/pci/intel/ivsc/mei_csi.h | 60 ++++
> include/linux/ivsc.h | 74 ++++
> 10 files changed, 1090 insertions(+)
> create mode 100644 drivers/media/pci/intel/ivsc/Kconfig
> create mode 100644 drivers/media/pci/intel/ivsc/Makefile
> create mode 100644 drivers/media/pci/intel/ivsc/ivsc.c
> create mode 100644 drivers/media/pci/intel/ivsc/mei_ace.c
> create mode 100644 drivers/media/pci/intel/ivsc/mei_ace.h
> create mode 100644 drivers/media/pci/intel/ivsc/mei_csi.c
> create mode 100644 drivers/media/pci/intel/ivsc/mei_csi.h
> create mode 100644 include/linux/ivsc.h

--
Regards,

Laurent Pinchart