Re: [PATCH 10/54] dt-bindings: display: panel-lvds: Document panel compatibles

On Wed, Aug 18, 2021 at 7:43 AM Maxime Ripard [off-list ref] wrote:

Hi Rob, Sam,

On Wed, Jul 21, 2021 at 08:29:47PM -0600, Rob Herring wrote:

quoted

On Wed, Jul 21, 2021 at 04:03:40PM +0200, Maxime Ripard wrote:

quoted

The binding mentions that all the drivers using that driver must use a
vendor-specific compatible but never enforces it, nor documents the
vendor-specific compatibles.

Let's make we document all of them, and that the binding will create an
error if we add one that isn't.

Cc: dri-devel@lists.freedesktop.org
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Sam Ravnborg <redacted>
Cc: Thierry Reding <redacted>
Signed-off-by: Maxime Ripard <redacted>
---
 .../bindings/display/panel/lvds.yaml           | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/panel/lvds.yaml b/Documentation/devicetree/bindings/display/panel/lvds.yaml
index 49460c9dceea..d1513111eb48 100644
--- a/Documentation/devicetree/bindings/display/panel/lvds.yaml
+++ b/Documentation/devicetree/bindings/display/panel/lvds.yaml

@@ -31,12 +31,18 @@ allOf:

 properties:
   compatible:
-    contains:
-      const: panel-lvds
-    description:
-      Shall contain "panel-lvds" in addition to a mandatory panel-specific
-      compatible string defined in individual panel bindings. The "panel-lvds"
-      value shall never be used on its own.
+    items:
+      - enum:
+          - advantech,idk-1110wr

At least this one is documented elsewhere.

Indeed, I missed it.

quoted

You can add 'minItems: 2' if you want to just enforce having 2 compatibles. Or do:

items:
  - {}
  - const: panel-lvds

Which also enforces the order.

It's not just about the order since a missing compatible will also raise
a warning.

Some of those panels have a binding of their own, but some probably
won't (and I can't find anything specific about the one I'm most
interested in: tbs,a711-panel)

Can we have something like:

compatible:
  oneOf:
    - items:
      - enum:
        - tbs,a711-panel
      - const: panel-lvds

    - items:
      - {}
      - const: panel-lvds

That would work for both cases I guess?

No, both conditions will be true. If you use 'anyOf', then we're never
really checking the specific compatible.

I think the problem here is trying to mix a common binding (aka an
incomplete collection of properties) and a specific binding. The
former is characterized with 'additionalProperties: true' as we have
here. You need to create a 'panel-simple-lvds.yaml' schema file that
references this one, defines all the 'simple' compatibles, and sets
'unevaluatedProperties: false'.

Rob