From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guennadi Liakhovetski Date: Mon, 08 Oct 2012 21:14:01 +0000 Subject: Re: [PATCH 04/14] media: add V4L2 DT binding documentation Message-Id: List-Id: References: <1348754853-28619-1-git-send-email-g.liakhovetski@gmx.de> <507330E6.1010409@wwwdotorg.org> <4043536.qVaHVXMbPA@avalon> In-Reply-To: <4043536.qVaHVXMbPA@avalon> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Laurent Pinchart Cc: linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Mark Brown , Magnus Damm , Hans Verkuil , Sylwester Nawrocki , linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Mon, 8 Oct 2012, Laurent Pinchart wrote: > On Monday 08 October 2012 14:00:38 Stephen Warren wrote: > > On 10/02/2012 08:33 AM, Guennadi Liakhovetski wrote: > > > On Tue, 2 Oct 2012, Rob Herring wrote: > > >> On 09/27/2012 09:07 AM, Guennadi Liakhovetski wrote: > > >>> This patch adds a document, describing common V4L2 device tree bindings. > > >>> > > >>> diff --git a/Documentation/devicetree/bindings/media/v4l2.txt > > >>> b/Documentation/devicetree/bindings/media/v4l2.txt>> > > >> One other comment below: > > >>> + > > >>> +General concept > > >>> +--------------- > > >>> + > > >>> +Video pipelines consist of external devices, e.g. camera sensors, > > >>> controlled +over an I2C, SPI or UART bus, and SoC internal IP blocks, > > >>> including video DMA +engines and video data processors. > > >>> + > > >>> +SoC internal blocks are described by DT nodes, placed similarly to > > >>> other SoC +blocks. External devices are represented as child nodes of > > >>> their respective bus +controller nodes, e.g. I2C. > > >>> + > > >>> +Data interfaces on all video devices are described by "port" child DT > > >>> nodes. +Configuration of a port depends on other devices participating > > >>> in the data +transfer and is described by "link" DT nodes, specified as > > >>> children of the +"port" nodes: > > >>> + > > >>> +/foo { > > >>> + port@0 { > > >>> + link@0 { ... }; > > >>> + link@1 { ... }; > > >>> + }; > > >>> + port@1 { ... }; > > >>> +}; > > >>> + > > >>> +If a port can be configured to work with more than one other device on > > >>> the same +bus, a "link" child DT node must be provided for each of > > >>> them. If more than one +port is present on a device or more than one > > >>> link is connected to a port, a +common scheme, using "#address-cells," > > >>> "#size-cells" and "reg" properties is +used. > > >>> + > > >>> +Optional link properties: > > >>> +- remote: phandle to the other endpoint link DT node. > > >> > > >> This name is a little vague. Perhaps "endpoint" would be better. > > > > > > "endpoint" can also refer to something local like in USB case. Maybe > > > rather the description of the "remote" property should be improved? > > > > The documentation doesn't show up in all the .dts files that use it; it > > might be useful to try and make the .dts file as obviously readable as > > possible. > > > > Perhaps "remote-port" or "connected-port" would be sufficiently descriptive. > > I like remote-port better than the already proposed remote-link. Yes, remote-port sounds better, than remote-link, but might be more difficult to correlate with the fact, that the phandle value of this property points to a link DT node, and not to a port. Thanks Guennadi > > (and yes, I know I'm probably bike-shedding now). > > -- > Regards, > > Laurent Pinchart > --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/