On 10/07/16 13:55, Hans Verkuil wrote:
On 07/10/2016 02:10 PM, Lars-Peter Clausen wrote:
On 07/09/2016 11:36 PM, Steve Longerbeam wrote:
On 07/09/2016 02:10 PM, Steve Longerbeam wrote:
On 07/09/2016 11:59 AM, Steve Longerbeam wrote:
On 07/07/2016 07:52 AM, Lars-Peter Clausen wrote:
On 07/07/2016 12:59 AM, Steve Longerbeam wrote:
Add a device tree boolean property "bt656-4" to allow setting
the ITU-R BT.656-4 compatible bit.
Signed-off-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx>
+ /* select ITU-R BT.656-4 compatible? */
Please don't use the '-4': BT.656 is sufficient. The -4 is just the version
number of the standard (and 5 is the latest anyway).
From the ADV7180 DS [1]:
BT.656-4, ITU-R BT.656-4 Enable, Address 0x04[7]
Between Revision 3 and Revision 4 of the ITU-R BT.656 standards, the ITU
has changed the toggling position for the V bit within the SAV EAV codes
for NTSC. The ITU-R BT.656-4 standard bit allows the user to select an
output mode that is compliant with either the previous or new standard.
For further information, visit the International Telecommunication Union
website.
Note that the standard change only affects NTSC and has no bearing on PAL.
When ITU-R BT.656-4 is 0 (default), the ITU-R BT.656-3 specification is
used. The V bit goes low at EAV of Line 10 and Line 273.
When ITU-R BT.656-4 is 1, the ITU-R BT.656-4 specification is used. The
V bit goes low at EAV of Line 20 and Line 283.
[1]www.analog.com/media/en/technical-documentation/data-sheets/*ADV7180*.pdf
+ if (of_property_read_bool(client->dev.of_node, "bt656-4"))
+ state->bt656_4 = true;
This property needs to be documented. In my opinion it should also be a
property of the endpoint sub-node rather than the toplevel device node
since
this is a configuration of the endpoint format.
Agreed, it's really a config of the backend capture endpoint. I'll move it
there and also document it in
Documentation/devicetree/bindings/media/i2c/adv7180.txt.
er, scratch that. ITU-R BT.656 compatibility is really a property of the
bt.656 bus. It
should be added to v4l2 endpoints and parsed by v4l2_of_parse_endpoint().
I've created
a patch to add a "bt656-mode" property to v4l2 endpoints and will copy all
the maintainers.
But I'm going back and forth on whether this property should be added to the
adv7180's
local endpoint, or to the remote endpoint. I'm leaning towards the remote
endpoint, since
this is more about how the backend wants the bus configured.
I think it should be set for both, as both endpoints need to agree on the
format.
Is it needed at all? Setting the polarity flags to H/VSYNC_ACTIVE_HIGH/LOW
will already signal BT.656 mode. See include/media/v4l2-mediabus.h and
v4l2-of.c.
I haven't looked in detail at adv7180, so I may have missed something, but this
looks strange.
Regards,
Hans
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