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Date:   Wed, 17 Aug 2022 10:14:45 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Sakari Ailus <sakari.ailus@linux.intel.com>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Paul Menzel <pmenzel@molgen.mpg.de>,
        Wang Yating <yating.wang@intel.com>,
        Christoph Jechlitschek <christoph.jechlitschek@intel.com>,
        Hao Yao <hao.yao@intel.com>, Andy Yeh <andy.yeh@intel.com>,
        Bingbu Cao <bingbu.cao@intel.com>,
        Tianshu Qiu <tian.shu.qiu@intel.com>,
        linux-media@vger.kernel.org, Mark Pearson <markpearson@lenovo.com>,
        Dell.Client.Kernel@dell.com, linux-kernel@vger.kernel.org,
        Guenter Roeck <groeck@google.com>,
        Andy Whitcroft <apw@canonical.com>,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        Christian Schaller <cschalle@redhat.com>,
        Wouter Bolsterlee <wouter@bolsterl.ee>,
        Miguel Palhas <mpalhas@gmail.com>,
        it+linux-media@molgen.mpg.de, "Hu, Jerry W" <jerry.w.hu@intel.com>
Subject: Re: Missing MIPI IPU6 camera driver for Intel Alder Lake laptops
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On Wed, Aug 17, 2022 at 08:09:16AM +0000, Sakari Ailus wrote:
> V4L2 + MC are not great APIs for supporting hardware such as IPU6 and
> coming up with an alternative is a major and risky endeavour. I expect many
> developers of drivers for similar hardware are in the same situation.

What has been done to help maybe make those apis work properly for this
hardware?  The hardware design pipeline is very long, this isn't
anything new that people just suddenly realized was going to need to
have full support on Linux.

> The hardware is getting increasingly complex and while there is some
> standardisation in the industry, it's mainly focussed on interoperatibility
> on hardware level rather than control interfaces or defining how a given
> feature is to be implemented.

Hardware standardization isn't an issue here, it's having working Linux
code to support all the crazy devices.

> As the camera is no longer a single, integrated device in this context but
> multiple devices from different vendors, there still remains a larger
> requirement for interoperability between, at the very least, cameras and
> CSI-2 receivers --- that in turn increasingly often are integrated in Image
> Signal Processors such as IPU6. This further raises the bar for an
> interface that would better support these devices.

Ok, great, what type of api would work for this hardware?  You all have
access to the hardware, know how it works, and know how userspace needs
to consume it.  So why not work to create the needed kernel support for
this now?  What is the causing the delay?

thanks,

greg k-h