Re: [PATCH v2 00/30] v4l: add support for multiplexed streams

From: "Niklas Söderlund" <niklas.soderlund@ragnatech.se>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Benoit Parrot <bparrot@ti.com>,
	linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH v2 00/30] v4l: add support for multiplexed streams
Date: Wed, 5 Dec 2018 23:09:50 +0100	[thread overview]
Message-ID: <20181205220950.GA17972@bigcity.dyn.berto.se> (raw)
In-Reply-To: <20181203221628.rzb7sz5purso4uak@kekkonen.localdomain>

Hi Sakari,

Thanks for your feedback.

On 2018-12-04 00:16:29 +0200, Sakari Ailus wrote:
> Hi Niklas,
> 
> On Fri, Nov 02, 2018 at 12:31:14AM +0100, Niklas Sï¿½derlund wrote:
> > Hi all,
> > 
> > This series adds support for multiplexed streams within a media device
> > link. The use-case addressed in this series covers CSI-2 Virtual
> > Channels on the Renesas R-Car Gen3 platforms. The v4l2 changes have been
> > a joint effort between Sakari and Laurent and floating around for some
> > time [1].
> > 
> > I have added driver support for the devices used on the Renesas Gen3
> > platforms, a ADV7482 connected to the R-Car CSI-2 receiver. With these
> > changes I can control which of the analog inputs of the ADV7482 the
> > video source is captured from and on which CSI-2 virtual channel the
> > video is transmitted on to the R-Car CSI-2 receiver.
> > 
> > The series adds two new subdev IOCTLs [GS]_ROUTING which allows
> > user-space to get and set routes inside a subdevice. I have added RFC
> > support for these to v4l-utils [2] which can be used to test this
> > series, example:
> > 
> >     Check the internal routing of the adv748x csi-2 transmitter:
> >     v4l2-ctl -d /dev/v4l-subdev24 --get-routing
> >     0/0 -> 1/0 [ENABLED]
> >     0/0 -> 1/1 []
> >     0/0 -> 1/2 []
> >     0/0 -> 1/3 []
> > 
> > 
> >     Select that video should be outputed on VC 2 and check the result:
> >     $ v4l2-ctl -d /dev/v4l-subdev24 --set-routing '0/0 -> 1/2 [1]'
> > 
> >     $ v4l2-ctl -d /dev/v4l-subdev24 --get-routing
> >     0/0 -> 1/0 []
> >     0/0 -> 1/1 []
> >     0/0 -> 1/2 [ENABLED]
> >     0/0 -> 1/3 []
> > 
> > This series is tested on R-Car M3-N and for your testing needs this
> > series is available at
> > 
> >     git://git.ragnatech.se/linux v4l2/mux
> > 
> > * Changes since v1
> > - Rebased on latest media-tree.
> > - Incorporated changes to patch 'v4l: subdev: compat: Implement handling 
> >   for VIDIOC_SUBDEV_[GS]_ROUTING' by Sakari.
> > - Added review tags.
> 
> I was looking at the patches and they seem very nice to me. It's not that
> I've written most of them, but I still. X-)

:-)

> 
> I noticed that the new [GS]_ROUTING interface has no documentation
> currently. Could you write it?

Will add it for the next version. Thanks for pointing this out.

> 
> Also what I'd like to see is the media graph of a device that is driven by
> these drivers. That'd help to better understand the use case also for those
> who haven't worked with the patches.

I will attach the media graph for this simple use-case with the adv7482 
and a more complex case using 8 cameras and GMSL in the next version.

-- 
Regards,
Niklas Sï¿½derlund