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

[Hans Verkuil]

On 06/09/2017 05:31 PM, Rob Herring wrote:
> On Fri, Jun 9, 2017 at 9:11 AM, Hans Verkuil <hverkuil at xs4all.nl> wrote:
>> On 09/06/17 16:07, Rob Herring wrote:
>>> On Wed, Jun 07, 2017 at 04:46:14PM +0200, Hans Verkuil wrote:
>>>> From: Hans Verkuil <hans.verkuil at cisco.com>
>>>>
>>>> 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 <hans.verkuil at cisco.com>
>>>> Cc: Krzysztof Kozlowski <krzk at kernel.org>
>>>> Cc: Andrzej Hajda <a.hajda at samsung.com>
>>>> Cc: devicetree at 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.
> 
>> 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 at 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