Re: [PATCH v11 01/10] dt-bindings: mediatek,dp: Add Display Port binding

[Rob Herring <robh@kernel.org>]

On Thu, Jun 16, 2022 at 09:22:16PM +0800, Rex-BC Chen wrote:
> On Tue, 2022-06-14 at 14:23 -0600, Rob Herring wrote:
> > On Fri, Jun 10, 2022 at 06:55:13PM +0800, Bo-Chen Chen wrote:
> > > From: Markus Schneider-Pargmann <msp@baylibre.com>
> > > 
> > > This controller is present on several mediatek hardware. Currently
> > > mt8195 and mt8395 have this controller without a functional
> > > difference,
> > > so only one compatible field is added.
> > > 
> > > The controller can have two forms, as a normal display port and as
> > > an
> > > embedded display port.
> > > 
> > > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > > [Bo-Chen: Fix reviewers' comment]
> > > Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> > > ---
> > >  .../display/mediatek/mediatek,dp.yaml         | 101
> > > ++++++++++++++++++
> > >  1 file changed, 101 insertions(+)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/display/mediatek/mediatek,dp.yaml
> > > 
> > > diff --git
> > > a/Documentation/devicetree/bindings/display/mediatek/mediatek,dp.ya
> > > ml
> > > b/Documentation/devicetree/bindings/display/mediatek/mediatek,dp.ya
> > > ml
> > > new file mode 100644
> > > index 000000000000..10f50a0dcf49
> > > --- /dev/null
> > > +++
> > > b/Documentation/devicetree/bindings/display/mediatek/mediatek,dp.ya
> > > ml
> > > @@ -0,0 +1,101 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: 
> > > https://urldefense.com/v3/__http://devicetree.org/schemas/display/mediatek/mediatek,dp.yaml*__;Iw!!CTRNKA9wMg0ARbw!yqAl1KhfbHqHN7-5aeqhzqeOVhPU_Z5beko5q-y-s5pcfp1WL5oVGvY5UF4EfWm4PWjc5mjBwyBUMsr_RI45ipbhsw$
> > >  
> > > +$schema: 
> > > https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!yqAl1KhfbHqHN7-5aeqhzqeOVhPU_Z5beko5q-y-s5pcfp1WL5oVGvY5UF4EfWm4PWjc5mjBwyBUMsr_RI5WzYKENQ$
> > >  
> > > +
> > > +title: MediaTek Display Port Controller
> > > +
> > > +maintainers:
> > > +  - Chun-Kuang Hu <chunkuang.hu@kernel.org>
> > > +  - Jitao shi <jitao.shi@mediatek.com>
> > > +
> > > +description: |
> > > +  Device tree bindings for the MediaTek display port and
> > > +  embedded display port controller present on some MediaTek SoCs.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - mediatek,mt8195-dp-tx
> > > +      - mediatek,mt8195-edp-tx
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  nvmem-cells:
> > > +    maxItems: 1
> > > +    description: efuse data for display port calibration
> > > +
> > > +  nvmem-cell-names:
> > > +    const: dp_calibration_data
> > > +
> > > +  power-domains:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  ports:
> > > +    $ref: /schemas/graph.yaml#/properties/ports
> > > +    properties:
> > > +      port@0:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: Input endpoint of the controller, usually
> > > dp_intf
> > > +
> > > +      port@1:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: Output endpoint of the controller
> > > +
> > > +    required:
> > > +      - port@0
> > > +      - port@1
> > > +
> > > +  max-lanes:
> > > +    maxItems: 1
> > > +    description: maximum number of lanes supported by the
> > > hardware.
> > 
> > We already have a 'data-lanes' property defined in 
> > 'video-interfaces.yaml' that can serve this purpose.
> > 
> 
> Hello Rob,
> 
> Thanks for review.
> From the description of video-interfaces.yaml, I think it's not quite
> match what we need. We only need this value be one of "1,2,4".

data-lanes = <0>;
data-lanes = <0 1>;
data-lanes = <0 1 2 3>;

Limiting the number of lanes to something less than the max is exactly 
how this property is used in addition to being able to show the mapping 
of lanes.

Rob