[PATCH] dt-bindings: display: bridge: lt9211: Require data-lanes on DSI input ports

[PATCH] dt-bindings: display: bridge: lt9211: Require data-lanes on DSI input ports

[Marek Vasut]

The Lontium LT9211 is capable of 1..4 DSI lanes per input DSI port,
describe the lane count for each input port in the schema.

Signed-off-by: Marek Vasut <marex@nabladev.com>
---
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robert Foss <rfoss@kernel.org>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: devicetree@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
---
NOTE: For example Linux kernel driver does already use that information
      and fails to probe if it is missing. There are currently no intree
      users for this binding, so no new warnings will be generated once
      this is applied, but a new user is about to be added.
---
 .../display/bridge/lontium,lt9211.yaml        | 37 ++++++++++++++++++-
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
index 9a6e9b25d14a9..5264fb2b68b78 100644
--- a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
@@ -36,18 +36,50 @@ properties:
 
     properties:
       port@0:
-        $ref: /schemas/graph.yaml#/properties/port
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
         description:
           Primary MIPI DSI port-1 for MIPI input or
           LVDS port-1 for LVDS input or DPI input.
 
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+            properties:
+              data-lanes:
+                description: array of physical DSI data lane indexes.
+                minItems: 1
+                items:
+                  - const: 1
+                  - const: 2
+                  - const: 3
+                  - const: 4
+
       port@1:
-        $ref: /schemas/graph.yaml#/properties/port
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
         description:
           Additional MIPI port-2 for MIPI input or LVDS port-2
           for LVDS input. Used in combination with primary
           port-1 to drive higher resolution displays
 
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+            properties:
+              data-lanes:
+                description: array of physical DSI data lane indexes.
+                minItems: 1
+                items:
+                  - const: 1
+                  - const: 2
+                  - const: 3
+                  - const: 4
+
       port@2:
         $ref: /schemas/graph.yaml#/properties/port
         description:
@@ -99,6 +131,7 @@ examples:
             reg = <0>;
 
             endpoint {
+              data-lanes = <1 2 3 4>;
               remote-endpoint = <&dsi0_out>;
             };
           };
-- 
2.53.0

Re: [PATCH] dt-bindings: display: bridge: lt9211: Require data-lanes on DSI input ports

[Krzysztof Kozlowski]

On Sat, Apr 04, 2026 at 05:40:18AM +0200, Marek Vasut wrote:
> The Lontium LT9211 is capable of 1..4 DSI lanes per input DSI port,
> describe the lane count for each input port in the schema.
> 
> Signed-off-by: Marek Vasut <marex@nabladev.com>
> ---
> Cc: Andrzej Hajda <andrzej.hajda@intel.com>
> Cc: Conor Dooley <conor+dt@kernel.org>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
> Cc: Jonas Karlman <jonas@kwiboo.se>
> Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Neil Armstrong <neil.armstrong@linaro.org>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Robert Foss <rfoss@kernel.org>
> Cc: Simona Vetter <simona@ffwll.ch>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: devicetree@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> ---
> NOTE: For example Linux kernel driver does already use that information
>       and fails to probe if it is missing. There are currently no intree

The first sentence must be part of the commit msg. That is important
reason why you are doing this... but I don't see how you achieve any of
this. Look:


>       users for this binding, so no new warnings will be generated once
>       this is applied, but a new user is about to be added.

What warnings? How?

> ---
>  .../display/bridge/lontium,lt9211.yaml        | 37 ++++++++++++++++++-
>  1 file changed, 35 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
> index 9a6e9b25d14a9..5264fb2b68b78 100644
> --- a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
> @@ -36,18 +36,50 @@ properties:
>  
>      properties:
>        port@0:
> -        $ref: /schemas/graph.yaml#/properties/port
> +        $ref: /schemas/graph.yaml#/$defs/port-base

OK, that's correct.

> +        unevaluatedProperties: false
>          description:
>            Primary MIPI DSI port-1 for MIPI input or
>            LVDS port-1 for LVDS input or DPI input.
>  
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false

That's correct.

> +
> +            properties:
> +              data-lanes:
> +                description: array of physical DSI data lane indexes.
> +                minItems: 1
> +                items:
> +                  - const: 1
> +                  - const: 2
> +                  - const: 3
> +                  - const: 4

That's almost redundant in this context - it was already there - and the
point is that it solves noting in the problem you had. Binding still
does not validate the ABI and does not match it, still.

Since commit foo bar, driver needs data-lanes, so what you need to do is
allow them and to require them. You can also specify their constraints
if device can be configured multiple ways, up to 4 lanes.

Best regards,
Krzysztof

Re: [PATCH] dt-bindings: display: bridge: lt9211: Require data-lanes on DSI input ports

[Marek Vasut]

On 4/7/26 10:00 AM, Krzysztof Kozlowski wrote:

>> NOTE: For example Linux kernel driver does already use that information
>>        and fails to probe if it is missing. There are currently no intree
> 
> The first sentence must be part of the commit msg. That is important
> reason why you are doing this... but I don't see how you achieve any of
> this. Look:
> 
> 
>>        users for this binding, so no new warnings will be generated once
>>        this is applied, but a new user is about to be added.
> 
> What warnings? How?

There are no in-tree users of this binding, so no DT checker warnings 
will be produced on existing in-tree DTs. I am in the process of adding 
a DTO which uses this binding now in arm64: dts: imx8mm: imx8mp: Add 
DTOs for Data Modul i.MX8M Mini and Plus eDM SBC

>> ---
>>   .../display/bridge/lontium,lt9211.yaml        | 37 ++++++++++++++++++-
>>   1 file changed, 35 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
>> index 9a6e9b25d14a9..5264fb2b68b78 100644
>> --- a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
>> +++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
>> @@ -36,18 +36,50 @@ properties:
>>   
>>       properties:
>>         port@0:
>> -        $ref: /schemas/graph.yaml#/properties/port
>> +        $ref: /schemas/graph.yaml#/$defs/port-base
> 
> OK, that's correct.
> 
>> +        unevaluatedProperties: false
>>           description:
>>             Primary MIPI DSI port-1 for MIPI input or
>>             LVDS port-1 for LVDS input or DPI input.
>>   
>> +        properties:
>> +          endpoint:
>> +            $ref: /schemas/media/video-interfaces.yaml#
>> +            unevaluatedProperties: false
> 
> That's correct.
> 
>> +
>> +            properties:
>> +              data-lanes:
>> +                description: array of physical DSI data lane indexes.
>> +                minItems: 1
>> +                items:
>> +                  - const: 1
>> +                  - const: 2
>> +                  - const: 3
>> +                  - const: 4
> 
> That's almost redundant in this context - it was already there - and the
> point is that it solves noting in the problem you had. Binding still
> does not validate the ABI and does not match it, still.
> 
> Since commit foo bar, driver needs data-lanes, so what you need to do is
> allow them and to require them. You can also specify their constraints
> if device can be configured multiple ways, up to 4 lanes.
Please pardon my ignorance, what exactly do you propose I change in this 
patch ?

Re: [PATCH] dt-bindings: display: bridge: lt9211: Require data-lanes on DSI input ports

[Krzysztof Kozlowski]

On 07/04/2026 16:51, Marek Vasut wrote:
> On 4/7/26 10:00 AM, Krzysztof Kozlowski wrote:
> 
>>> NOTE: For example Linux kernel driver does already use that information
>>>        and fails to probe if it is missing. There are currently no intree
>>
>> The first sentence must be part of the commit msg. That is important
>> reason why you are doing this... but I don't see how you achieve any of
>> this. Look:
>>
>>
>>>        users for this binding, so no new warnings will be generated once
>>>        this is applied, but a new user is about to be added.
>>
>> What warnings? How?
> 
> There are no in-tree users of this binding, so no DT checker warnings 
> will be produced on existing in-tree DTs. I am in the process of adding 
> a DTO which uses this binding now in arm64: dts: imx8mm: imx8mp: Add 
> DTOs for Data Modul i.MX8M Mini and Plus eDM SBC

So add new user, apply this and what warnings are you seeing?

> 
>>> ---
>>>   .../display/bridge/lontium,lt9211.yaml        | 37 ++++++++++++++++++-
>>>   1 file changed, 35 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
>>> index 9a6e9b25d14a9..5264fb2b68b78 100644
>>> --- a/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
>>> +++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt9211.yaml
>>> @@ -36,18 +36,50 @@ properties:
>>>   
>>>       properties:
>>>         port@0:
>>> -        $ref: /schemas/graph.yaml#/properties/port
>>> +        $ref: /schemas/graph.yaml#/$defs/port-base
>>
>> OK, that's correct.
>>
>>> +        unevaluatedProperties: false
>>>           description:
>>>             Primary MIPI DSI port-1 for MIPI input or
>>>             LVDS port-1 for LVDS input or DPI input.
>>>   
>>> +        properties:
>>> +          endpoint:
>>> +            $ref: /schemas/media/video-interfaces.yaml#
>>> +            unevaluatedProperties: false
>>
>> That's correct.
>>
>>> +
>>> +            properties:
>>> +              data-lanes:
>>> +                description: array of physical DSI data lane indexes.
>>> +                minItems: 1
>>> +                items:
>>> +                  - const: 1
>>> +                  - const: 2
>>> +                  - const: 3
>>> +                  - const: 4
>>
>> That's almost redundant in this context - it was already there - and the
>> point is that it solves noting in the problem you had. Binding still
>> does not validate the ABI and does not match it, still.
>>
>> Since commit foo bar, driver needs data-lanes, so what you need to do is
>> allow them and to require them. You can also specify their constraints
>> if device can be configured multiple ways, up to 4 lanes.
> Please pardon my ignorance, what exactly do you propose I change in this 
> patch ?

Follow the subject - require data-lanes. That's was the main point of
this change, no?

Best regards,
Krzysztof

Re: [PATCH] dt-bindings: display: bridge: lt9211: Require data-lanes on DSI input ports

[Krzysztof Kozlowski]

On Sat, Apr 04, 2026 at 05:40:18AM +0200, Marek Vasut wrote:
> The Lontium LT9211 is capable of 1..4 DSI lanes per input DSI port,
> describe the lane count for each input port in the schema.

Ah, and subject does not really match what you did in the patch. It will
match when you fix the patch, though...

Best regards,
Krzysztof