Re: [PATCHv2] dt: bindings: Add support for CSI1 bus

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Hi Baruch,

On Thu, Jan 12, 2017 at 02:06:03PM +0200, Baruch Siach wrote:
> Hi Pavel,
> 
> On Wed, Jan 11, 2017 at 11:53:35PM +0100, Pavel Machek wrote:
> > From: Sakari Ailus <sakari.ailus@xxxxxx>
> > 
> > In the vast majority of cases the bus type is known to the driver(s)
> > since a receiver or transmitter can only support a single one. There
> > are cases however where different options are possible.
> > 
> > The existing V4L2 OF support tries to figure out the bus type and
> > parse the bus parameters based on that. This does not scale too well
> > as there are multiple serial busses that share common properties.
> > 
> > Some hardware also supports multiple types of busses on the same
> > interfaces.
> > 
> > Document the CSI1/CCP2 property strobe. It signifies the clock or
> > strobe mode.
> >  
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxx>
> > Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@xxxxxxxxx>
> > Signed-off-by: Pavel Machek <pavel@xxxxxx>
> > 
> > diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
> > index 9cd2a36..08c4498 100644
> > --- a/Documentation/devicetree/bindings/media/video-interfaces.txt
> > +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
> > @@ -76,6 +76,11 @@ Optional endpoint properties
> >    mode horizontal and vertical synchronization signals are provided to the
> >    slave device (data source) by the master device (data sink). In the master
> >    mode the data source device is also the source of the synchronization signals.
> > +- bus-type: data bus type. Possible values are:
> > +  0 - MIPI CSI2
> > +  1 - parallel / Bt656
> 
> Why not have separate values for parallel and BT.656?

The current implementation of V4L2 OF support digs the information from
other properties (hsync-active, vsync-active and field-even-active). If any
of them are present, the bus is considered to be a regular parallel bus ---
the Bt.656 has no such signals.

CSI-2 bus is assumed if CSI-2 specific properties can be found. However,
explicit bus type is needed as the type of the bus isn't anymore implicitly
determinable with the addition of CSI-1 and CCP2 busses: they use the same
properties.

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@xxxxxx	XMPP: sailus@xxxxxxxxxxxxxx
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