Re: [Ksummit-discuss] [TECH TOPIC] Media Controller

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Thu, Aug 6, 2015 at 11:20 AM, Mauro Carvalho Chehab
<mchehab@osg.samsung.com> wrote:
> Along the years, we've been developing a mechanism at the Kernel to store
> and present graphs to userspace, called Media Controller. The original
> scope of the Media Controller were to store and represent pipeline connections
> between hardware components on complex streaming devices, like the ones
> that are used on cell phones, where there are typically two camera sensors,
> and lots of processing units to enhance the image and to convert it into
> different formats.
>
> Since the beginning, we found that it would be useful to use it some day
> on other subsystems. Well, now such day has come ;)
>
> Driven by the need of using the media controller on TV sets, where the
> pipelines can be really complex and may cover more than one subsystem,
> we're reworking at both the core implementation and at the userspace API
> to allow it to be used where needed.
>
> On a TV set, the streaming data pipeline covers camera sensors, analog TV,
> digital TV, crypto/decrypto modules, audio and GPU. Also, TVs have network
> interfaces that may be provided via DVB (like CATV). If we want/need to
> represent and control the full pipeline, the media controller has to have
> support on different subsystems: V4L2, DVB, ALSA, DRM and Network. It also
> needs a way to share a common struct between those subsystems without making
> them depend on each other. So, it should use devres.
>
> Also, on the MC summit, it was pointed that other subsystems like IIO
> (Linux Industrial I/O) have similar needs and also need to track complex
> pipelines.
>
> When we have such complex pipelines that interact with different subsystems,
> we need to better describe the interfaces between userspace and the
> pipeline. In the past, we only needed to represent device nodes, but now
> we'll need to be capable of representing network interfaces and sysfs.
>
> We also need to allow dynamic changes in terms of removing and adding
> objects at the graph.
>
> Due to that, we're redesigning the MC core, making it more generic and
> more capable of representing complex devices. So, we'd like to discuss
> it with the KS audience, in order to check if there are other use cases
> for it, and if the solution we're designing would require more changes
> to fit such other use cases.
>
> For this discussion, I nominate myself and Laurent Pinchart, Hans Verkuil,
> Sakari Ailus, Shuah Khan and Lars-Peter Clausen.

There's ideas for live sources/sinks to connect kms/drm drivers with
v4l drivers. I want to participate too to discuss possible integration
issues with drm. Dave Airlie should probably be there too.
-Daniel

> PS.: I know we're a week late, but we've been busy this month with the
> discussions, including a Media Controller 3-days summit in Helsinki last
> week.
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch