Re: [RFC PATCH] [media]: of: move graph helpers from drivers/media/v4l2-core to drivers/of

[Grant Likely]

On Tue, 18 Feb 2014 08:06:24 +0100, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote:
> Hi Grant,
> 
> On Mon, Feb 17, 2014 at 06:14:51PM +0000, Grant Likely wrote:
> > On Tue, 11 Feb 2014 07:56:33 -0600, Rob Herring <robherring2@xxxxxxxxx> wrote:
> > > On Tue, Feb 11, 2014 at 5:45 AM, Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> wrote:
> > > > From: Philipp Zabel <philipp.zabel@xxxxxxxxx>
> > > >
> > > > This patch moves the parsing helpers used to parse connected graphs
> > > > in the device tree, like the video interface bindings documented in
> > > > Documentation/devicetree/bindings/media/video-interfaces.txt, from
> > > > drivers/media/v4l2-core to drivers/of.
> > > 
> > > This is the opposite direction things have been moving...
> > > 
> > > > This allows to reuse the same parser code from outside the V4L2 framework,
> > > > most importantly from display drivers. There have been patches that duplicate
> > > > the code (and I am going to send one of my own), such as
> > > > http://lists.freedesktop.org/archives/dri-devel/2013-August/043308.html
> > > > and others that parse the same binding in a different way:
> > > > https://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg100761.html
> > > >
> > > > I think that all common video interface parsing helpers should be moved to a
> > > > single place, outside of the specific subsystems, so that it can be reused
> > > > by all drivers.
> > > 
> > > Perhaps that should be done rather than moving to drivers/of now and
> > > then again to somewhere else.
> > 
> > This is just parsing helpers though, isn't it? I have no problem pulling
> > helper functions into drivers/of if they are usable by multiple
> > subsystems. I don't really understand the model being used though. I
> > would appreciate a description of the usage model for these functions
> > for poor folks like me who can't keep track of what is going on in
> > subsystems.
> 
> You can find it under Documentation/devicetree/bindings/media/video-interfaces.txt

Okay, I think I'm okay with moving the helpers, but I will make one
requirement. I would like to have a short binding document describing
the pattern being used. The document above talks a lot about video
specific issues, but the helpers appear to be specifically about the
tree walking properties of the API.

g.
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