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

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> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Sent: Wednesday, February 15, 2023 5:43 PM
> 
> 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 ?

Not sure, but the first step is to upstream this driver.

> 
> > 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 ?

No camera data will be allowed to go through IVSC, and then there will be no data on IVSC CSI transmitter side. 

> 
> > 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




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