Hi Sylwester, On Saturday 25 May 2013 16:11:52 Sylwester Nawrocki wrote: > 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. I prefer 1. over 2. > 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 ? My gut feeling is that we should have separate properties for the video sync type and the synchronization signals polarities. We could have a chip that supports sync-on-green on the analog (input) side and outputs separate hsync and vsync signals only on the digital (output) side. There would be no sync- on-green polarity in that case. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
