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Date: Sat, 09 May 2015 11:31:42 +0200
From: Hans Verkuil <hverkuil@xs4all.nl>
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To: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
CC: Linux Media Mailing List <linux-media@vger.kernel.org>,
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Subject: Re: [PATCH 07/18] media controller: rename the tuner entity
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>>> Brainstorming:
>>>
>>> It might be better to map each device node to an entity and each hardware
>>> component (tuner, DMA engine) to an entity, and avoid this mixing of
>>> hw entity vs device node entity.

There are two options here:

either make each device node an entity, or expose the device node information
as properties of an entity.

The latter would be backwards compatible with what we do today. I'm trying to
think of reasons why you would want to make each device node an entity in its
own right.

The problem today is that a video_device representing a video/vbi/radio/swradio
device node is an entity, but it is really representing the dma engine. Which
is weird for radio devices since there is no dma engine there.

Implementing device nodes as entities in their own right does solve this problem,
but implementing it as properties would be weird since a radio device node would
be a property of a radio tuner entity, which can be a subdevice driver which means
that the bridge driver would have to add the radio device property to a subdev
driver, which feels really wrong to me.

With this in mind I do think representing device nodes as entities in their own
right makes sense. But I would do this also for a v4l-subdev node. It's very
inconsistent not to do that.

Regards,

	Hans