Hi Sylwester,

On Fri, May 24, 2013 at 4:41 PM, Sylwester Nawrocki
[off-list ref] wrote:

Prabhakar,


On 05/16/2013 03:18 PM, Lad Prabhakar wrote:

quoted

From: Lad, Prabhakar <prabhakar.csengg@gmail.com>

This patch adds "sync-on-green" property as part of
endpoint properties and also support to parse them in the parser.

quoted

--- a/Documentation/devicetree/bindings/media/video-interfaces.txt
+++ b/Documentation/devicetree/bindings/media/video-interfaces.txt

@@ -101,6 +101,8 @@ Optional endpoint properties
    array contains only one entry.
  - clock-noncontinuous: a boolean property to allow MIPI CSI-2

non-continuous
    clock mode.
+-sync-on-green: a boolean property indicating to sync with the green
signal in
+ RGB.

Are you sure this is what you need for the TVP7002 chip ?

Yes

I think we should differentiate between analog and digital signals and the
related
device's configuration. AFAIU for the analog part there can be various video
sychronisation methods, i.e. ways in which the synchronisation signals are
transmitted along side the video component (RGB or luma/chroma) signals.
According
to [1] (presumably not most reliable source of information) there are
following
methods of transmitting sync signals:

 - Separate sync
 - Composite sync
 - Sync-on-green (SOG)
 - Sync-on-luminance
 - Sync-on-composite

And all these seem to refer to analog video signal.

I was about to add all these but as per Laurent mentioned we can add this
whenever there is a need of it.

From looking at Figure 8 "TVP7002 Application Example" in the TVP7002's
datasheet
([2], p. 52) and your initial TVP7002 patches it looks like what you want is
to
specify polarity of the SOGOUT signal, so the processor that receives this
signal
can properly interpret it, is it correct ?

Yes

If so then wouldn't it be more appropriate to define e.g. 'sog-active'
property
and media bus flags:
        V4L2_MBUS_SYNC_ON_GREEN_ACTIVE_LOW
        V4L2_MBUS_SYNC_ON_GREEN_ACTIVE_HIGH
?

Agreed I'll add these flags.

And for synchronisation method on the analog part we could perhaps define
'component-sync' or similar property that would enumerate all possible
synchronisation methods. We might as well use separate boolean properties,
but I'm a bit concerned about the increasing number of properties that need
to be parsed for each parallel video bus "endpoint".

I am not clear on it can please elaborate more on this.

Regards,
--Prabhakar Lad