Re: [RFC PATCH 3/4] dt-bindings: panel: Introduce dual-link LVDS panel

From: AngeloGioacchino Del Regno
Date: Tue Jan 03 2023 - 06:52:11 EST


Il 03/01/23 07:46, Aradhya Bhatia ha scritto:
Dual-link LVDS interfaces have 2 links, with even pixels traveling on
one link, and odd pixels on the other. These panels are also generic in
nature, with no documented constraints, much like their single-link
counterparts, "panel-lvds".

Add a new compatible, "panel-dual-lvds", and a dt-binding document for
these panels.

Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
---
.../display/panel/panel-dual-lvds.yaml | 157 ++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 158 insertions(+)
create mode 100644 Documentation/devicetree/bindings/display/panel/panel-dual-lvds.yaml

diff --git a/Documentation/devicetree/bindings/display/panel/panel-dual-lvds.yaml b/Documentation/devicetree/bindings/display/panel/panel-dual-lvds.yaml
new file mode 100644
index 000000000000..88a7aa2410be
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/panel/panel-dual-lvds.yaml
@@ -0,0 +1,157 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/panel-dual-lvds.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic Dual-Link LVDS Display Panel
+
+maintainers:
+ - Aradhya Bhatia <a-bhatia1@xxxxxx>
+ - Thierry Reding <thierry.reding@xxxxxxxxx>
+
+description: |
+ A dual-LVDS interface is a dual-link connection with the even pixels
+ traveling on one link, and the odd pixels traveling on the other.
+
+allOf:
+ - $ref: panel-common.yaml#
+ - $ref: /schemas/display/lvds.yaml/#
+
+properties:
+ compatible:
+ oneOf:
+ - items:
+ - enum:
+ - lincolntech,lcd185-101ct
+ - microtips,13-101hieb0hf0-s
+ - const: panel-dual-lvds
+ - const: panel-dual-lvds
+
+ ports:
+ $ref: /schemas/graph.yaml#/properties/ports
+
+ properties:
+ port@0:
+ $ref: /schemas/graph.yaml#/$defs/port-base
+ unevaluatedProperties: false
+ description: The sink for first set of LVDS pixels.
+
+ properties:
+ dual-lvds-odd-pixels:
+ type: boolean
+
+ dual-lvds-even-pixels:
+ type: boolean
+
+ oneOf:
+ - required: [dual-lvds-odd-pixels]

One question: why do we need a "panel-dual-lvds" compatible?
A Dual-LVDS panel is a LVDS panel using two ports, hence still a panel-lvds.

If you're doing this to clearly distinguish, for human readability purposes,
single-link vs dual-link panels, I think that this would still be clear even
if we use panel-lvds alone because dual-link panels, as you wrote in this
binding, does *require* two ports, with "dual-lvds-{odd,even}-pixels" properties.

So... the devicetree node would look like this:

panel {
compatible = "vendor,panel", "panel-lvds";
....
ports {
port@0 {
.....
-> dual-lvds-odd-pixels <-
}

port@1 {
.....
-> dual-lvds-even-pixels <-
};
};
};

+ - required: [dual-lvds-even-pixels]

...Though, if you expect dual-lvds panels to get other quirks in the future,
that's a whole different story and you may actually need the panel-dual-lvds
compatible.

Regards,
Angelo