Re: [PATCH v1 3/6] dt-bindings: display: tegra: Document 8-bit CPU parallel interface

[Thierry Reding <thierry.reding@kernel.org>]

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On Wed, Sep 30, 2026 at 12:00:21PM +0300, Svyatoslav Ryhel wrote:
> ср, 30 вер. 2026 р. о 11:47 Thierry Reding <thierry.reding@kernel.org> пише:
> >
> > On Wed, Sep 30, 2026 at 10:05:32AM +0300, Svyatoslav Ryhel wrote:
> > > Document 8-bit CPU parallel MIPI DBI Type B interface provided by
> > > Tegra20/30 SoCs display controller.
> > >
> > > Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> > > ---
> > >  .../display/tegra/nvidia,tegra-8bit-cpu.yaml  | 138 ++++++++++++++++++
> > >  1 file changed, 138 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/display/tegra/nvidia,tegra-8bit-cpu.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/tegra/nvidia,tegra-8bit-cpu.yaml b/Documentation/devicetree/bindings/display/tegra/nvidia,tegra-8bit-cpu.yaml
> > > new file mode 100644
> > > index 0000000000000..f0dab608b2936
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/display/tegra/nvidia,tegra-8bit-cpu.yaml
> > > @@ -0,0 +1,138 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/display/tegra/nvidia,tegra-8bit-cpu.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Nvidia Tegra DC based MIPI DBI Type B bridge
> > > +
> > > +maintainers:
> > > +  - Svyatoslav Ryhel <clamor95@gmail.com>
> > > +
> > > +description: The display controller in Tegra20/30 SoCs features an
> > > +  8-bit SPI interface that closely resembles the MIPI DBI Type B
> > > +  protocol and is referred to as '8-bit CPU'. Each display controller
> > > +  provides two such interfaces, which can be used to send MIPI DCS
> > > +  commands to initialize and control the panel while image data is
> > > +  transmitted via 16/18/24-line RGB.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: nvidia,tegra-8bit-cpu
> >
> > The description says that this is a feature of the display controller,
> > so adding a new binding and compatible string for this is not the right
> > move. This is all covered by the "nvidia,tegra{20,30}-dc" already, just
> > need to extend that with whatever is new.
> >
> 
> How would you model it? I have tried to model 8bit-cpu as a bridge, similar
> to how DSI bridges are modeled. This reflects interface used to link RGB and
> panel, without inflating existing DC binding. If you have any ideas in modelling
> this, I am open to any suggestions.

My suggestion is to integrate this into the existing "rgb" node, or, if
that becomes too convoluted, a separate "lcd" node (or "dbi", whatever).

Thierry

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