Re: [PATCHv2 1/3] dt-bindings: display: dw_hdmi.txt: add cec-disable property

2018-07-02 Thread Hans Verkuil
On 29/06/18 09:17, Neil Armstrong wrote:
> Hi Hans,
> 
> On 03/04/2018 10:27, Hans Verkuil wrote:
>> On 27/03/18 00:25, Rob Herring wrote:
>>> On Fri, Mar 23, 2018 at 01:59:13PM +0100, Hans Verkuil wrote:
 From: Hans Verkuil 

 Some boards have both a DesignWare and their own CEC controller.
 The CEC pin is only hooked up to their own CEC controller and not
 to the DW controller.

 Add the cec-disable property to disable the DW CEC controller.

 This particular situation happens on Amlogic boards that have their
 own meson CEC controller.
>>>
>>> Seems like we could avoid this by describing how the CEC line is hooked 
>>> up which could be needed for other reasons.
>>
>> So there are three situations:
>>
>> 1) The cec pin is connected to the DW HDMI TX. That's already supported.
>> 2) The cec pin is not connected at all, but the CEC IP is instantiated.
>>We need the cec-disable property for that. This simply states that the
>>CEC pin is not connected.
>> 3) The cec pin is connected to an HDMI RX. We do not support this at the
>>moment. If we want to support this, then we need a 'hdmi-rx' phandle
>>that points to the HDMI receiver that the CEC pin is associated with.
>>This will be similar to the already existing 'hdmi-phandle' property
>>used to associate a CEC driver with an HDMI transmitter. In hindsight
>>it would have been better if 'hdmi-phandle' was named 'hdmi-tx' :-(
>>
>> I can make a binding proposal for 3, but I have no hardware to test it,
>> so I think it is better to add this only when someone has hardware. It
>> will require quite a few changes to the driver and likely also the CEC core.
> 
> Can't we simply add a property to override the HW config fields in this case ?
> It will be then usable with any feature the is enabled by reading the config
> bits like AHB Audio, I2c, CEC, ... and maybe many more in the future.

Yes, we can do that as well. But is that a proper description of the hardware?
The HW *does* support CEC, but in this case the CEC line is just not hooked
up to anything. So overriding the HW config field doesn't really sound right
to me.

I still believe that the cec-disable property in order to describe situation
2 in the list above is the right approach.

Perhaps giving it a different name (cec-not-connected?) helps overcome Rob's
objections? Rob?

Sorry for not following up on this earlier.

Regards,

Hans

> 
> Neil
> 
>>
>> Regards,
>>
>>  Hans
>>
>>>

 Signed-off-by: Hans Verkuil 
 Acked-by: Neil Armstrong 
 ---
  Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt | 3 +++
  1 file changed, 3 insertions(+)
>>
> 
> 
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Re: [PATCHv2 1/3] dt-bindings: display: dw_hdmi.txt: add cec-disable property

2018-06-29 Thread Neil Armstrong
Hi Hans,

On 03/04/2018 10:27, Hans Verkuil wrote:
> On 27/03/18 00:25, Rob Herring wrote:
>> On Fri, Mar 23, 2018 at 01:59:13PM +0100, Hans Verkuil wrote:
>>> From: Hans Verkuil 
>>>
>>> Some boards have both a DesignWare and their own CEC controller.
>>> The CEC pin is only hooked up to their own CEC controller and not
>>> to the DW controller.
>>>
>>> Add the cec-disable property to disable the DW CEC controller.
>>>
>>> This particular situation happens on Amlogic boards that have their
>>> own meson CEC controller.
>>
>> Seems like we could avoid this by describing how the CEC line is hooked 
>> up which could be needed for other reasons.
> 
> So there are three situations:
> 
> 1) The cec pin is connected to the DW HDMI TX. That's already supported.
> 2) The cec pin is not connected at all, but the CEC IP is instantiated.
>We need the cec-disable property for that. This simply states that the
>CEC pin is not connected.
> 3) The cec pin is connected to an HDMI RX. We do not support this at the
>moment. If we want to support this, then we need a 'hdmi-rx' phandle
>that points to the HDMI receiver that the CEC pin is associated with.
>This will be similar to the already existing 'hdmi-phandle' property
>used to associate a CEC driver with an HDMI transmitter. In hindsight
>it would have been better if 'hdmi-phandle' was named 'hdmi-tx' :-(
> 
> I can make a binding proposal for 3, but I have no hardware to test it,
> so I think it is better to add this only when someone has hardware. It
> will require quite a few changes to the driver and likely also the CEC core.

Can't we simply add a property to override the HW config fields in this case ?
It will be then usable with any feature the is enabled by reading the config
bits like AHB Audio, I2c, CEC, ... and maybe many more in the future.

Neil

> 
> Regards,
> 
>   Hans
> 
>>
>>>
>>> Signed-off-by: Hans Verkuil 
>>> Acked-by: Neil Armstrong 
>>> ---
>>>  Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt | 3 +++
>>>  1 file changed, 3 insertions(+)
> 


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Re: [PATCHv2 1/3] dt-bindings: display: dw_hdmi.txt: add cec-disable property

2018-04-03 Thread Hans Verkuil
On 27/03/18 00:25, Rob Herring wrote:
> On Fri, Mar 23, 2018 at 01:59:13PM +0100, Hans Verkuil wrote:
>> From: Hans Verkuil 
>>
>> Some boards have both a DesignWare and their own CEC controller.
>> The CEC pin is only hooked up to their own CEC controller and not
>> to the DW controller.
>>
>> Add the cec-disable property to disable the DW CEC controller.
>>
>> This particular situation happens on Amlogic boards that have their
>> own meson CEC controller.
> 
> Seems like we could avoid this by describing how the CEC line is hooked 
> up which could be needed for other reasons.

So there are three situations:

1) The cec pin is connected to the DW HDMI TX. That's already supported.
2) The cec pin is not connected at all, but the CEC IP is instantiated.
   We need the cec-disable property for that. This simply states that the
   CEC pin is not connected.
3) The cec pin is connected to an HDMI RX. We do not support this at the
   moment. If we want to support this, then we need a 'hdmi-rx' phandle
   that points to the HDMI receiver that the CEC pin is associated with.
   This will be similar to the already existing 'hdmi-phandle' property
   used to associate a CEC driver with an HDMI transmitter. In hindsight
   it would have been better if 'hdmi-phandle' was named 'hdmi-tx' :-(

I can make a binding proposal for 3, but I have no hardware to test it,
so I think it is better to add this only when someone has hardware. It
will require quite a few changes to the driver and likely also the CEC core.

Regards,

Hans

> 
>>
>> Signed-off-by: Hans Verkuil 
>> Acked-by: Neil Armstrong 
>> ---
>>  Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt | 3 +++
>>  1 file changed, 3 insertions(+)

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Re: [PATCHv2 1/3] dt-bindings: display: dw_hdmi.txt: add cec-disable property

2018-03-26 Thread Rob Herring
On Fri, Mar 23, 2018 at 01:59:13PM +0100, Hans Verkuil wrote:
> From: Hans Verkuil 
> 
> Some boards have both a DesignWare and their own CEC controller.
> The CEC pin is only hooked up to their own CEC controller and not
> to the DW controller.
> 
> Add the cec-disable property to disable the DW CEC controller.
> 
> This particular situation happens on Amlogic boards that have their
> own meson CEC controller.

Seems like we could avoid this by describing how the CEC line is hooked 
up which could be needed for other reasons.

> 
> Signed-off-by: Hans Verkuil 
> Acked-by: Neil Armstrong 
> ---
>  Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt | 3 +++
>  1 file changed, 3 insertions(+)
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[PATCHv2 1/3] dt-bindings: display: dw_hdmi.txt: add cec-disable property

2018-03-23 Thread Hans Verkuil
From: Hans Verkuil 

Some boards have both a DesignWare and their own CEC controller.
The CEC pin is only hooked up to their own CEC controller and not
to the DW controller.

Add the cec-disable property to disable the DW CEC controller.

This particular situation happens on Amlogic boards that have their
own meson CEC controller.

Signed-off-by: Hans Verkuil 
Acked-by: Neil Armstrong 
---
 Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt 
b/Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt
index 33bf981fbe33..4a13f4858bc0 100644
--- a/Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt
+++ b/Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt
@@ -27,6 +27,9 @@ responsible for defining whether each property is required or 
optional.
   - "isfr" is the internal register configuration clock (mandatory).
   - "cec" is the HDMI CEC controller main clock (optional).
 
+- cec-disable: Do not use the DWC CEC controller since the CEC line is not
+  hooked up even though the CEC DWC IP is present.
+
 - ports: The connectivity of the DWC HDMI TX with the rest of the system is
   expressed in using ports as specified in the device graph bindings defined
   in Documentation/devicetree/bindings/graph.txt. The numbering of the ports
-- 
2.15.1

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