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

[Wu, Wentong]

> -----Original Message-----
> From: Bingbu Cao <bingbu.cao@xxxxxxxxxxxxxxx>
> Sent: Friday, February 17, 2023 9:44 AM
> 
> Hi, Sakari,
> 
> On 2/16/23 9:12 PM, Sakari Ailus wrote:
> > Hi Bingbu, Wentong,
> >
> > On Wed, Feb 15, 2023 at 08:09:50PM +0800, Bingbu Cao wrote:
> >>
> >> Hi, Wentong,
> >>
> >> On 2/15/23 5:43 PM, Laurent Pinchart wrote:
> >>> 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 ?
> 
> As I know, without IVSC, once user enable the privacy mode, the Intel
> Converged Security Engine will configure the IPU camera mask (security register),
> which will mask the specific CSI2 port and produce dummy imaging data. For the
> case with IVSC, there is no final solution on Linux so far I think.
> 
> Wentong, is IVSC trying to cut off the stream and then notify user and IPU?

yes

> 
> >>>
> >>
> >> Continue with question from Laurent,
> >>
> >> How IVSC handle the privacy request from user? Is there some
> >> notification mechanism to user-space?

IVSC has already defined privacy callback for host IPU/camera driver.

> > I'd have concern if IVSC driver
> >> need private callback to request back-end(e.g. ISP driver) to handle stream
> cutting.
> >
> > How does the privacy mode work, does it just pass zeroes (or other
> > dummy
> > data) towards the host or nothing?

No data on CSI transmitter side

> >
> > A V4L2 control can be used for the purpose of passing the information
> > to the user space at least.

I will take some time to review V4L2 sub-device and control mechanism, and then update the driver.

BR,
Wentong  

> >
> 
> --
> Best regards,
> Bingbu Cao