Em Fri, 10 Mar 2017 15:20:48 +0100
Hans Verkuil [off-list ref] escreveu:

quoted

As I've already mentioned, from talking about this with Mauro, it seems
Mauro is in agreement with permitting the control inheritence... I wish
Mauro would comment for himself, as I can't quote our private discussion
on the subject.  

I can't comment either, not having seen his mail and reasoning.

The rationale is that we should support the simplest use cases first.

In the case of the first MC-based driver (and several subsequent
ones), the simplest use case required MC, as it was meant to suport
a custom-made sophisticated application that required fine control
on each component of the pipeline and to allow their advanced
proprietary AAA userspace-based algorithms to work.

That's not true, for example, for the UVC driver. There, MC
is optional, as it should be.

quoted

Right now, my view is that v4l2 is currently being screwed up by people
with different opinions - there is no unified concensus on how any of
this stuff is supposed to work, everyone is pulling in different
directions.  That needs solving _really_ quickly, so I suggest that
v4l2 people urgently talk to each other and thrash out some of the
issues that Steve's patch set has brought up, and settle on a way
forward, rather than what is seemingly happening today - which is
everyone working in isolation of everyone else with their own bias on
how things should be done.  

The simple fact is that to my knowledge no other MC applications inherit
controls from subdevs. Suddenly doing something different here seems very
wrong to me and needs very good reasons.

That's because it was not needed before, as other subdev-based drivers
are meant to be used only on complex scenarios with custom-made apps.

Thanks,
Mauro