Hi Laurent,
On Sun, 5 Jul 2026 at 23:35, Laurent Pinchart
<[email protected]> wrote:
> Since DDC version 2, introduced in 1996, VGA monitors have exposed EDID
> data over an I2C bus. The bus is also used to detect the presence of a
> connected monitor by trying to read the EDID data.
>
> Some devices where the VGA display is integrated in the device and
> always connected do not connect the DDC pins. Some development boards,
> such as the Renesas M3N Salvator-XS, also do not connect the DDC pins.
>
> To support those, add the ability to provide hardcoded EDID data in the
> device tree. This is mutually exclusive with specifying a DDC bus, and
> can only be done when the VGA display is guaranteed to be always
> connected.
>
> Signed-off-by: Laurent Pinchart <[email protected]>
Thanks for your patch!
> --- a/Documentation/devicetree/bindings/display/connector/vga-connector.yaml
> +++ b/Documentation/devicetree/bindings/display/connector/vga-connector.yaml
> @@ -19,10 +19,25 @@ properties:
> description: phandle link to the I2C controller used for DDC EDID probing
> $ref: /schemas/types.yaml#/definitions/phandle
>
> + edid:
> + $ref: /schemas/types.yaml#/definitions/uint8-array
> + description:
> + When the DDC signals are not wired to the connector, and the connected
> + display is not removable, this property is used to supply a binary EDID
> + blob for the display.
> +
> port:
> $ref: /schemas/graph.yaml#/properties/port
> description: Connection to controller providing VGA signals
>
> +allOf:
> + - if:
> + required:
> + - ddc-i2c-bus
> + then:
> + properties:
> + edid: false
> +
What if the DDC signals are wired to the connector on the provider side,
but not on the consumer side?
A DT overlay describing the consumer device can add an edid property,
but it cannot delete the ddc-i2c-bus property in the base DTB.
> required:
> - compatible
> - port
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
