Messages in this thread | | | Date | Sat, 25 May 2013 16:11:52 +0200 | From | Sylwester Nawrocki <> | Subject | Re: [PATCH RFC v2] media: OF: add sync-on-green endpoint property |
| |
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
| |