Messages in this thread | | | Date | Mon, 28 Aug 2017 10:27:51 -0300 | From | Mauro Carvalho Chehab <> | Subject | V4L2 device node centric - Was: [PATCH v4 6/7] media: videodev2: add a flag for MC-centric devices |
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Em Mon, 28 Aug 2017 11:41:58 +0200 Hans Verkuil <hverkuil@xs4all.nl> escreveu:
> > + control, and thus can't be used by **v4l2-centric** applications. > > vdev-centric > > TBD: I still think I prefer V4L2-centric over vdev-centric.
I'm splitting it on a separate thread, to make easier for us to discuss.
For those that aren't tracking the patchset that are documenting those terms, when MC was added, we got a hole new series of V4L2 devices that are incompatible with standard V4L2 applications, as they require knowledge about the hardware sub-devices. We are referring to such devices as MC-centric. We need another term to refer to the V4L2 devices that can be used by a generic application, and are fully controlled via a V4L2 device (/dev/video*, /dev/radio*, /dev/swradio*, /dev/vbi*, /dev/v4l-touch*).
The proposed documentation patch series solves this issue by adding a glossary (patch 1) that defines what a "V4L2 device node" as:
V4L2 device node A device node that it is associated to a V4L2 main driver, as specified at :ref:`v4l2_device_naming`.
And, at the device naming chapter, at the spec (patch 2), it explicitly lists all V4L2 device node names:
.. _v4l2_device_naming:
V4L2 Device Node Naming =======================
... The existing V4L2 device node types are:
======================== ====================================================== Default device node name Usage ======================== ====================================================== ``/dev/videoX`` Video input/output devices ``/dev/vbiX`` Vertical blank data (i.e. closed captions, teletext) ``/dev/radioX`` Radio tuners and modulators ``/dev/swradioX`` Software Defined Radio tuners and modulators ``/dev/v4l-touchX`` Touch sensors ======================== ======================================================
So, the concept of "V4L2 Device Node" is now clear, and doesn't include V4L2 sub-device device nodes (/dev/v4l-subdev*).
For devices controlled via media controller, everybody seems to be comfortable of calling them as MC-centric.
There are currently two proposals to refer to the media hardware that is controlled via a V4L2 Device Node:
- vdev-centric - V4L2-centric
The last one sounds confusing to me, as subdev API is part of the V4L2 specification. "V4L2-centric" name sounds to include subdevs.
That's why IMHO, vdev-centric is better.
We could go to some other naming for them, that would also be an alias for "V4L2 Device Node":
- VD-centric - VDN-centric
Comments?
Thanks, Mauro
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