Re: [PATCH 7/9] dt-bindings: media/s5p-cec.txt: document needs-hpd property

On 06/09/2017 05:31 PM, Rob Herring wrote:

On Fri, Jun 9, 2017 at 9:11 AM, Hans Verkuil [off-list ref] wrote:

quoted

On 09/06/17 16:07, Rob Herring wrote:

quoted

On Wed, Jun 07, 2017 at 04:46:14PM +0200, Hans Verkuil wrote:

quoted

From: Hans Verkuil <redacted>

Needed for boards that wire the CEC pin in such a way that it
is unavailable when the HPD is low.

Signed-off-by: Hans Verkuil <redacted>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Andrzej Hajda <redacted>
Cc: devicetree@vger.kernel.org
---
 Documentation/devicetree/bindings/media/s5p-cec.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/media/s5p-cec.txt b/Documentation/devicetree/bindings/media/s5p-cec.txt
index 4bb08d9d940b..261af4d1a791 100644
--- a/Documentation/devicetree/bindings/media/s5p-cec.txt
+++ b/Documentation/devicetree/bindings/media/s5p-cec.txt

@@ -17,6 +17,12 @@ Required properties:
   - samsung,syscon-phandle - phandle to the PMU system controller
   - hdmi-phandle - phandle to the HDMI controller

+Optional:
+  - needs-hpd : if present the CEC support is only available when the HPD
+    is high. Some boards only let the CEC pin through if the HPD is high, for
+    example if there is a level converter that uses the HPD to power up
+    or down.

Seems like something common. Can you document in a common location?

Should we do the same with hdmi-phandle? It is also used by CEC drivers to find
the HDMI driver.

Yes.

quoted

Currently only used by s5p-cec and stih-cec, but there will be more.

I guess this would be a sensible place to document this:

Documentation/devicetree/bindings/media/cec.txt

Sounds good. You can do this as a follow-up to this patch if you want.
For this one:

Acked-by: Rob Herring <robh@kernel.org>

Sorry, I have what might be a stupid question: should I update the s5p-cec.txt
to refer to the cec.txt bindings file for the hdmi-phandle and needs-hpd instead
of describing it here? It seems pointless to do that for the hdmi-phandle, but
it might make more sense for the needs-hpd property.

E.g.:

  - needs-hpd: CEC support is only present if HPD is high. See cec.txt for more
    details.


Proposed text for cec.txt:

-------------------------------------------------
Common bindings for HDMI CEC adapters

- hdmi-phandle: phandle to the HDMI controller.

- needs-hpd: if present the CEC support is only available when the HPD
  is high. Some boards only let the CEC pin through if the HPD is high, for
  example if there is a level converter that uses the HPD to power up
  or down.
-------------------------------------------------

Regards,

	Hans