Hi,
On 05/25/2013 11:17 AM, Prabhakar Lad wrote:
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.
I thought about two possible options:
1. single property 'component-sync' or 'video-sync' that would have values:
#define VIDEO_SEPARATE_SYNC 0x01
#define VIDEO_COMPOSITE_SYNC 0x02
#define VIDEO_SYNC_ON_COMPOSITE 0x04
#define VIDEO_SYNC_ON_GREEN 0x08
#define VIDEO_SYNC_ON_LUMINANCE 0x10
And we could put these definitions into a separate header, e.g.
<dt-bindings/video-interfaces.h>
Then in a device tree source file one could have, e.g.
video-sync = <VIDEO_SYNC_ON_GREEN>;
2. Separate boolean property for each video sync type, e.g.
"video-composite-sync"
"video-sync-on-composite"
"video-sync-on-green"
"video-sync-on-luminance"
Separate sync, with separate VSYNC, HSYNC lines, would be the default, when
none of the above is specified and 'vsync-active', 'hsync-active' properties
are present.
However, I suppose the better would be to deduce the video synchronisation
method from the sync signal polarity flags. Then, for instance, when an
endpoint node contains "composite-sync-active" property the parser would
determine the "composite sync" synchronisation type is used.
Thus it might make sense to have only following integer properties (added
as needed):
composite-sync-active
sync-on-green-active
sync-on-comp-active
sync-on-luma-active
This would allow to specify polarity of each signal and at the same time
the parsing code could derive synchronisation type. A new field could be
added to struct v4l2_of_parallel_bus, e.g. sync_type and it would be filled
within v4l2_of_parse_endpoint().
What do you think ?
Thanks,
Sylwester
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