linux-kernel - Re: [PATCH v2 1/3] dt-bindings: display: bridge: fork out ti,ds90c185 from lvds-transmitter

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Date:   Thu, 27 Dec 2018 22:53:55 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     Rob Herring <robh@...nel.org>, Peter Rosin <peda@...ator.liu.se>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        Mark Rutland <mark.rutland@....com>,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] dt-bindings: display: bridge: fork out ti,ds90c185
 from lvds-transmitter

On 2018-12-27 22:27, Rob Herring wrote:
> On Wed, Dec 19, 2018 at 02:04:47PM +0100, Peter Rosin wrote:
>> From: Peter Rosin <peda@...ntia.se>
>>
>> DS90C185 has a shutdown pin which does not fit in the lvds-transmitter
>> binding, which is meant to be generic.
>>
>> The sister chip DS90C187 is similar to DS90C185, describe it here as well.
>>
>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>> ---
>>  .../bindings/display/bridge/lvds-transmitter.txt   |  8 +---
>>  .../bindings/display/bridge/ti,ds90c185.txt        | 55 ++++++++++++++++++++++
>>  2 files changed, 56 insertions(+), 7 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,ds90c185.txt
>>
>> diff --git a/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt b/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
>> index 50220190c203..fd39ad34c383 100644
>> --- a/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
>> +++ b/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
>> @@ -22,13 +22,7 @@ among others.
>>  
>>  Required properties:
>>  
>> -- compatible: Must be one or more of the following
>> -  - "ti,ds90c185" for the TI DS90C185 FPD-Link Serializer
>> -  - "lvds-encoder" for a generic LVDS encoder device
>> -
>> -  When compatible with the generic version, nodes must list the
>> -  device-specific version corresponding to the device first
>> -  followed by the generic version.
>> +- compatible: Must be "lvds-encoder"
>>  
>>  Required nodes:
>>  
>> diff --git a/Documentation/devicetree/bindings/display/bridge/ti,ds90c185.txt b/Documentation/devicetree/bindings/display/bridge/ti,ds90c185.txt
>> new file mode 100644
>> index 000000000000..a13e778503e6
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/display/bridge/ti,ds90c185.txt
>> @@ -0,0 +1,55 @@
>> +Texas Instruments FPD-Link (LVDS) Serializer
>> +--------------------------------------------
>> +
>> +The DS90C185 and DS90C187 are low-power serializers for portable
>> +battery-powered applications that reduces the size of the RGB
>> +interface between the host GPU and the display.
>> +
>> +Required properties:
>> +
>> +- compatible: Should be
>> +  "ti,ds90c185", "lvds-encoder"  for the TI DS90C185 FPD-Link Serializer
>> +  "ti,ds90c187", "lvds-encoder"  for the TI DS90C187 FPD-Link Serializer
>> +
>> +Optional properties:
>> +
>> +- pwdn-gpios: Power down control GPIO (the PDB pin, active-low)
> 
> powerdown-gpios is the standard name.

The lvds-encoder driver handles this binding, and that driver incidentally
also implements the thine,thc63lvdm83d binding which already has a
pwdn-gpios property. Should the thine,thc63lvdm83d binding be updated and
the driver be made to support both properties?

Since the lvds-encoder driver never had support for the pwdn-gpios (at least
not upstream) I suppose there is also the option to simply go with
powerdown-gpios as you suggest and not bother with support for the
pwdn-gpios property.

I'm quite willing to send an updated series, but I don't know what is
preferred, and am in need of guidance.

Cheers,
Peter

>> +
>> +Required nodes:
>> +
>> +The devices have two video ports. Their connections are modeled using the OF
>> +graph bindings specified in Documentation/devicetree/bindings/graph.txt.
>> +
>> +- Video port 0 for parallel input
>> +- Video port 1 for LVDS output
>> +
>> +
>> +Example
>> +-------
>> +
>> +lvds-encoder {
>> +	compatible = "ti,ds90c185", "lvds-encoder";
>> +
>> +	pwdn-gpios = <&gpio 17 GPIO_ACTIVE_LOW>;
>> +
>> +	ports {
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		port@0 {
>> +			reg = <0>;
>> +
>> +			lvds_enc_in: endpoint {
>> +				remote-endpoint = <&lcdc_out_rgb>;
>> +			};
>> +		};
>> +
>> +		port@1 {
>> +			reg = <1>;
>> +
>> +			lvds_enc_out: endpoint {
>> +				remote-endpoint = <&lvds_panel_in>;
>> +			};
>> +		};
>> +	};
>> +};
>> -- 
>> 2.11.0
>>