From mboxrd@z Thu Jan 1 00:00:00 1970 From: mchehab@s-opensource.com (Mauro Carvalho Chehab) Date: Fri, 10 Mar 2017 12:53:42 -0300 Subject: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline In-Reply-To: References: <1487211578-11360-1-git-send-email-steve_longerbeam@mentor.com> <1487211578-11360-15-git-send-email-steve_longerbeam@mentor.com> <20170302160257.GK3220@valkosipuli.retiisi.org.uk> <20170303230645.GR21222@n2100.armlinux.org.uk> <20170304131329.GV3220@valkosipuli.retiisi.org.uk> <20170310130733.GU21222@n2100.armlinux.org.uk> <20170310140124.GV21222@n2100.armlinux.org.uk> Message-ID: <20170310125342.7f047acf@vento.lan> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Em Fri, 10 Mar 2017 15:20:48 +0100 Hans Verkuil escreveu: > > > 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. > > 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