Re: [PATCH v6 01/19] dt-bindings: display: imx: Add i.MX8qxp Display Controller processing units

[Rob Herring <robh@kernel.org>]

On Wed, Dec 11, 2024 at 11:05:52AM +0800, Liu Ying wrote:
> On 12/11/2024, Rob Herring wrote:
> > On Mon, Dec 09, 2024 at 11:39:05AM +0800, Liu Ying wrote:
> >> Freescale i.MX8qxp Display Controller is implemented as construction set of
> >> building blocks with unified concept and standardized interfaces.  Document
> >> all existing processing units.
> >>
> >> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> >> ---
> >> v6:
> >> * No change.
> >>
> >> v5:
> >> * Document aliases for processing units which have multiple instances in
> >>   the Display Controller.  Drop Rob's previous R-b tag. (Maxime)
> >>
> >> v4:
> >> * Collect Rob's R-b tag.
> >>
> >> v3:
> >> * Combine fsl,imx8qxp-dc-fetchunit-common.yaml,
> >>   fsl,imx8qxp-dc-fetchlayer.yaml and fsl,imx8qxp-dc-fetchwarp.yaml
> >>   into 1 schema doc fsl,imx8qxp-dc-fetchunit.yaml. (Rob)
> >> * Document all processing units. (Rob)
> >>
> >> v2:
> >> * Drop fsl,dc-*-id DT properties. (Krzysztof)
> >> * Add port property to fsl,imx8qxp-dc-tcon.yaml. (Krzysztof)
> >> * Fix register range sizes in examples.
> >>
> >>  .../display/imx/fsl,imx8qxp-dc-blitblend.yaml |  46 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-clut.yaml      |  49 ++++++
> >>  .../imx/fsl,imx8qxp-dc-constframe.yaml        |  49 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-dither.yaml    |  49 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-extdst.yaml    |  77 +++++++++
> >>  .../display/imx/fsl,imx8qxp-dc-fetchunit.yaml | 147 ++++++++++++++++++
> >>  .../display/imx/fsl,imx8qxp-dc-filter.yaml    |  47 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-framegen.yaml  |  68 ++++++++
> >>  .../display/imx/fsl,imx8qxp-dc-gammacor.yaml  |  38 +++++
> >>  .../imx/fsl,imx8qxp-dc-layerblend.yaml        |  45 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-matrix.yaml    |  48 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-rop.yaml       |  48 ++++++
> >>  .../display/imx/fsl,imx8qxp-dc-safety.yaml    |  34 ++++
> >>  .../imx/fsl,imx8qxp-dc-scaling-engine.yaml    |  89 +++++++++++
> >>  .../display/imx/fsl,imx8qxp-dc-signature.yaml |  58 +++++++
> >>  .../display/imx/fsl,imx8qxp-dc-store.yaml     | 100 ++++++++++++
> >>  .../display/imx/fsl,imx8qxp-dc-tcon.yaml      |  50 ++++++
> >>  17 files changed, 1042 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-blitblend.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-clut.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-constframe.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-dither.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-extdst.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-fetchunit.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-filter.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-framegen.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-gammacor.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-layerblend.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-matrix.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-rop.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-safety.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-scaling-engine.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-signature.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-store.yaml
> >>  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-tcon.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-blitblend.yaml b/Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-blitblend.yaml
> >> new file mode 100644
> >> index 000000000000..7f800e72c3f3
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/display/imx/fsl,imx8qxp-dc-blitblend.yaml
> >> @@ -0,0 +1,46 @@
> >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/display/imx/fsl,imx8qxp-dc-blitblend.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: Freescale i.MX8qxp Display Controller Blit Blend Unit
> >> +
> >> +description: |
> >> +  Combines two input frames to a single output frame, all frames having the
> >> +  same dimension.
> >> +
> >> +  Each Blit Blend Unit device should have an alias in the aliases node, in the
> >> +  form of dc<x>-blitblend<y>, where <x> is an integer specifying the Display
> >> +  Controller instance and <y> is an integer specifying the Blit Blend Unit
> >> +  device instance.
> > 
> > That's really an abuse of aliases. If you need to describe connections 
> > between components, use the graph binding like everyone else does for 
> > display path components.
> 
> I need to describe components' instance numbers which imply the connections
> between components but not vice versa. If I use the graph binding, I cannot
> get the instance numbers(0 or 1) of the two display engines(documented by
> fsl,imx8qxp-dc-display-engine.yaml). If you have no objections, I may add the
> instance numbers to compatible strings, like brcm,bcm2835-pixelvalve0.yaml.
> What do you think?

You could have dc<x> and blitblend<y> aliases and use the graph to 
define the connections. But I'm not really a fan of adding custom 
aliases either. Why are the instance numbers important?

Are the programming models or features of the instances different? If 
so, then a different compatible or property describing the feature may 
be appropriate.

Rob