Re: [PATCH v4 08/13] dt-bindings: display: Document dual-link LVDS display common properties

[Liu Ying <victor.liu@nxp.com>]

On 10/29/2024, Biju Das wrote:
> 
> Hi Liu Ying,

Hi Biju,

> 
>> -----Original Message-----
>> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of Liu Ying
>> Sent: 29 October 2024 07:35
>> Subject: Re: [PATCH v4 08/13] dt-bindings: display: Document dual-link LVDS display common properties
>>
>> On 10/29/2024, Biju Das wrote:
>>> Hi Liu Ying,
>>
>> Hi Biju,
>>
>>>
>>>> -----Original Message-----
>>>> From: Liu Ying <victor.liu@nxp.com>
>>>> Sent: 29 October 2024 07:13
>>>> Subject: Re: [PATCH v4 08/13] dt-bindings: display: Document
>>>> dual-link LVDS display common properties
>>>>
>>>> On 10/29/2024, Biju Das wrote:
>>>>> Hi Liu Ying,
>>>>
>>>> Hi Biju,
>>>>
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Liu Ying <victor.liu@nxp.com>
>>>>>> Sent: 29 October 2024 06:17
>>>>>> Subject: Re: [PATCH v4 08/13] dt-bindings: display: Document
>>>>>> dual-link LVDS display common properties
>>>>>>
>>>>>> On 10/28/2024, Liu Ying wrote:
>>>>>>> Dual-link LVDS displays receive odd pixels and even pixels
>>>>>>> separately from dual LVDS links.  One link receives odd pixels and
>>>>>>> the other receives even pixels.  Some of those displays may also
>>>>>>> use only one LVDS link to receive all pixels, being odd and even agnostic.
>>>>>>> Document common properties for those displays by extending LVDS
>>>>>>> display common properties defined in lvds.yaml.
>>>>>>>
>>>>>>> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>>>>>>> Signed-off-by: Liu Ying <victor.liu@nxp.com>
>>>>>>> ---
>>>>>>> v4:
>>>>>>> * Squash change for advantech,idk-2121wr.yaml and
>>>>>>>   panel-simple-lvds-dual-ports.yaml with lvds-dual-ports.yaml.
>>>>>>> (Rob)
>>>>>>> * Improve description in lvds-dual-ports.yaml.  (Krzysztof)
>>>>>>>
>>>>>>> v3:
>>>>>>> * New patch.  (Dmitry)
>>>>>>>
>>>>>>>  .../bindings/display/lvds-dual-ports.yaml     | 76 +++++++++++++++++++
>>>>>>>  .../display/panel/advantech,idk-2121wr.yaml   | 14 +---
>>>>>>>  .../panel/panel-simple-lvds-dual-ports.yaml   | 20 +----
>>>>>>>  3 files changed, 78 insertions(+), 32 deletions(-)  create mode
>>>>>>> 100644
>>>>>>> Documentation/devicetree/bindings/display/lvds-dual-ports.yaml
>>>>>>>
>>>>>>> diff --git
>>>>>>> a/Documentation/devicetree/bindings/display/lvds-dual-ports.yaml
>>>>>>> b/Documentation/devicetree/bindings/display/lvds-dual-ports.yaml
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..5f7a30640404
>>>>>>> --- /dev/null
>>>>>>> +++ b/Documentation/devicetree/bindings/display/lvds-dual-ports.ya
>>>>>>> +++ ml
>>>>>>> @@ -0,0 +1,76 @@
>>>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML
>>>>>>> +1.2
>>>>>>> +---
>>>>>>> +$id: http://devicetree.org/schemas/display/lvds-dual-ports.yaml#
>>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>>>> +
>>>>>>> +title: Dual-link LVDS Display Common Properties
>>>>>>> +
>>>>>>> +maintainers:
>>>>>>> +  - Liu Ying <victor.liu@nxp.com>
>>>>>>> +
>>>>>>> +description: |
>>>>>>> +  Common properties for LVDS displays with dual LVDS links.
>>>>>>> +Extend LVDS display
>>>>>>> +  common properties defined in lvds.yaml.
>>>>>>> +
>>>>>>> +  Dual-link LVDS displays receive odd pixels and even pixels
>>>>>>> + separately from  the dual LVDS links. One link receives odd
>>>>>>> + pixels and the other receives  even pixels. Some of those
>>>>>>> + displays may also use only one LVDS link to  receive all pixels, being odd and even agnostic.
>>>>>>> +
>>>>>>> +allOf:
>>>>>>> +  - $ref: lvds.yaml#
>>>>>>> +
>>>>>>> +properties:
>>>>>>> +  ports:
>>>>>>> +    $ref: /schemas/graph.yaml#/properties/ports
>>>>>>> +
>>>>>>> +    properties:
>>>>>>> +      port@0:
>>>>>>> +        $ref: /schemas/graph.yaml#/$defs/port-base
>>>>>>> +        unevaluatedProperties: false
>>>>>>> +        description: the first LVDS input link
>>>>>>> +
>>>>>>> +        properties:
>>>>>>> +          dual-lvds-odd-pixels:
>>>>>>> +            type: boolean
>>>>>>> +            description: the first LVDS input link for odd pixels
>>>>>>> +
>>>>>>> +          dual-lvds-even-pixels:
>>>>>>> +            type: boolean
>>>>>>> +            description: the first LVDS input link for even
>>>>>>> + pixels
>>>>>>> +
>>>>>>> +        oneOf:
>>>>>>> +          - required: [dual-lvds-odd-pixels]
>>>>>>> +          - required: [dual-lvds-even-pixels]
>>>>>>> +          - properties:
>>>>>>> +              dual-lvds-odd-pixels: false
>>>>>>> +              dual-lvds-even-pixels: false
>>>>>>> +
>>>>>>> +      port@1:
>>>>>>> +        $ref: /schemas/graph.yaml#/$defs/port-base
>>>>>>> +        unevaluatedProperties: false
>>>>>>> +        description: the second LVDS input link
>>>>>>> +
>>>>>>> +        properties:
>>>>>>> +          dual-lvds-odd-pixels:
>>>>>>> +            type: boolean
>>>>>>> +            description: the second LVDS input link for odd
>>>>>>> + pixels
>>>>>>> +
>>>>>>> +          dual-lvds-even-pixels:
>>>>>>> +            type: boolean
>>>>>>> +            description: the second LVDS input link for even
>>>>>>> + pixels
>>>>>>> +
>>>>>>> +        oneOf:
>>>>>>> +          - required: [dual-lvds-odd-pixels]
>>>>>>> +          - required: [dual-lvds-even-pixels]
>>>>>>> +          - properties:
>>>>>>> +              dual-lvds-odd-pixels: false
>>>>>>> +              dual-lvds-even-pixels: false
>>>>>>
>>>>>> Hmm, I should require port@0 or port@1.
>>>>>
>>>>> For dual LVDS, you need 3 ports as common use case
>>>>
>>>> For LVDS panels, only two ports for LVDS sink are needed.
>>>> For display bridges with LVDS sink, one additional output port is
>>>> needed.  However, I'm not sure if this output port should be
>>>> documented in this binding or not, because it doesn't look common enough considering the LVDS
>> panels.
>>>>
>>>>>
>>>>> 2 input ports and 1 outport and all are required properties.
>>>>
>>>> The output port cannot be required for LVDS panels at least.
>>>
>>> Ack.
>>>
>>>>
>>>> We need to require one or two input ports, because IT6263 may use one LVDS link or two.
>>>
>>> This patch is for generic dual link common cases and is not applicable for IT6263 single link case.
>>
>> Based on previous discussion(especially Dmitry's suggestion), this binding should cover display
>> bridges that can use one LVDS sink port or two LVDS sink ports, like IT6263.  To be clear, those
>> bridges may have two modes(supported by one
>> chip) - single LVDS sink link mode and dual LVDS sink link mode.  Those bridges are considered as
>> common dual-link LVDS displays.  That's why I was asked to extract the common
>> properties to this schema when adding IT6263 DT binding.
> 
> As per [1] and [2] both panels don’t support single LVDS link.
> IT6263 is bridge device that has single and dual link support.
> Not sure the single link case has to be taken care in ITE6263 binding itself,
> Leaving Dual link as it is??

There are a couple of bridges supporting dual-link LVDS like
IT6263, see lontium,lt9211.yaml and thine,thc63lvd1024.yaml.
So, it looks fine for this binding to cover those bridges,
as those LVDS links are sort of common stuff.

> 
> [1]
> https://elixir.bootlin.com/linux/v6.12-rc5/source/Documentation/devicetree/bindings/display/panel/advantech,idk-2121wr.yaml
> [2]
> 
> https://elixir.bootlin.com/linux/v6.12-rc5/source/Documentation/devicetree/bindings/display/panel/panel-simple-lvds-dual-ports.yaml
> 
> 
> Cheers,
> Biju

-- 
Regards,
Liu Ying