Re: [PATCH v2 2/2] media: i2c: tvp7002: add OF support

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On 07/11/2013 07:09 PM, Prabhakar Lad wrote:
[...]
diff --git a/Documentation/devicetree/bindings/media/i2c/tvp7002.txt
b/Documentation/devicetree/bindings/media/i2c/tvp7002.txt
new file mode 100644
index 0000000..9daebe1
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/i2c/tvp7002.txt
@@ -0,0 +1,43 @@
+* Texas Instruments TV7002 video decoder
+
[...]
+
+- ti,tvp7002-fid-polarity: Active-high Field ID polarity of the endpoint.

I thought it was agreed 'field-even-active' would be used instead of
this device specific property. Did you run into any issues with that ?


Argh I some how missed it out, sorry this should be 'field-even-active'

OK.

And include/media/tvp70002.h:

  * fid_polarity:
  *                      0 ->  the field ID output is set to logic 1 for an
odd
  *                           field (field 1) and set to logic 0 for an even
  *                           field (field 0).
  *                      1 ->  operation with polarity inverted.


Do you know if the chip automatically selects video sync source
(sync-on-green
vs. VSYNC/HSYNC) and there is no need to configure this on the analogue
input
side ? At least the driver seems to always select the default SOGIN_1 input
(TVP7002_IN_MUX_SEL_1 register is set only at initialization time).

Yes the driver is selecting the default SOGIN_1 input.

Or perhaps it just outputs on SOGOUT, VSOUT, HSOUT lines whatever is fed to
its analogue inputs, and any further processing unit need to determine what
synchronization signal is present and should be used ?


Yes that correct, there is a register (Sync Detect Status) which
detects the sync for you.

I suspect that we don't need, e.g. another endpoint node to specify the
configuration of the TVP7002 analogue input interface, that would contain
a property like video-sync.


If I understand correctly you mean if there are two tvp7002 devices connected
we don’t need to specify video-sync property, but my question how do we
specify this property in common then ?

No, I thought about two port sub-nodes of a single device node, one for the
TVP7002 video input and one for the output. But it seems there is no need
for that, i.e. to specify the input configuration statically in the firmware. The chip detects the signals automatically, i.e. it uses whatever is available,
and it allows querying the selection status at run time. What would really
need to be configured statically in DT in that case then ? Some initial video sync configuration ? I guess it could be well hard coded in the driver, since
the hardware does run time detection anyway.

It there are real use cases I gues we could add video-sync property or similar,
besides the existing signal polarity properties.

--
Thanks,
Sylwester
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