Date:   Thu, 16 Feb 2023 15:12:21 +0200
From:   Sakari Ailus <sakari.ailus@linux.intel.com>
To:     Bingbu Cao <bingbu.cao@linux.intel.com>
Cc:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Wentong Wu <wentong.wu@intel.com>, mchehab@kernel.org,
        linux-media@vger.kernel.org, srinivas.pandruvada@intel.com,
        pierre-louis.bossart@linux.intel.com, zhifeng.wang@intel.com,
        xiang.ye@intel.com, tian.shu.qiu@intel.com, bingbu.cao@intel.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/3] media: pci: intel: ivsc: Add driver of Intel
 Visual Sensing Controller(IVSC)
Message-ID: <Y+4rtSMArg5ow0Sh@kekkonen.localdomain>
References: <20230213022347.2480307-1-wentong.wu@intel.com>
 <Y+ypKYI4c6fHL4Eu@pendragon.ideasonboard.com>
 <00c5c16e-c94e-a328-06d9-5f09ad35258d@linux.intel.com>
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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 ?
> >
> 
> Continue with question from Laurent,
> 
> How IVSC handle the privacy request from user? Is there some notification
> mechanism to user-space? 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?

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

-- 
Regards,

Sakari Ailus