Re: [PATCH 2/5] dt-bindings: soc: imx93-media-blk-ctrl: Add LDB subnode into schema and example

[Conor Dooley <conor@kernel.org>]

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On Mon, Oct 23, 2023 at 08:27:20AM +0200, Alexander Stein wrote:
> Am Sonntag, 22. Oktober 2023, 19:39:12 CEST schrieb Conor Dooley:
> > On Fri, Oct 20, 2023 at 03:00:15PM +0200, Alexander Stein wrote:
> > > Document the LDB bridge subnode and add the subnode into the example.
> > > For the subnode to work, the block control must scan its subnodes and
> > > bind drivers to them, do not misuse either simple-bus or simple-mfd
> > > here.
> > > 
> > > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> > > ---
> > > 
> > >  .../soc/imx/fsl,imx93-media-blk-ctrl.yaml     | 44 +++++++++++++++++++
> > >  1 file changed, 44 insertions(+)
> > > 
> > > diff --git
> > > a/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ctrl.yaml
> > > b/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ctrl.yaml
> > > index b3554e7f9e76..5ba66dfb0e05 100644
> > > ---
> > > a/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ctrl.yaml
> > > +++
> > > b/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ctrl.yaml> 
> > > @@ -24,6 +24,12 @@ properties:
> > >    reg:
> > >      maxItems: 1
> > > 
> > > +  '#address-cells':
> > > +    const: 1
> > > +
> > > +  '#size-cells':
> > > +    const: 1
> > > +
> > > 
> > >    '#power-domain-cells':
> > >      const: 1
> > > 
> > > @@ -46,9 +52,16 @@ properties:
> > >        - const: csi
> > >        - const: dsi
> > > 
> > > +  bridge@20:
> > > +    type: object
> > > +    $ref: /schemas/display/bridge/fsl,ldb.yaml#
> > > +    unevaluatedProperties: false
> > > +
> > > 
> > >  required:
> > >    - compatible
> > >    - reg
> > > 
> > > +  - '#address-cells'
> > > +  - '#size-cells'
> > 
> > It seems to make little sense to me that these would become required
> > when the bridge is optional. Is it valid to have one of these
> > media-blk-ctrls without the ldb subnode?
> 
> fsl,imx93-media-blk-ctrl privides several power-domains (DSI, CSI, ISI, PXP 
> and LCDIF), currently unused. This series introduces the usage for LCDIF power 
> domain. LDB is the LVDS display bridge. So there are several power domains 
> which don't requires the usage of ldb.
> On the other hand I prefer consistency, so I opted to keep things similar to 
> commit 1cb0c87d27dc. If it shall not be added here, it should be removed in 
> Documentation/devicetree/bindings/soc/imx/fsl,imx8mp-media-blk-ctrl.yaml as 
> well.

IIRC the tooling will complain if you have an enabled node containing
#address-cells and/or #size-cells but no child nodes, so making
#address-cells or #size-cells required will cause problems. Looks like
the only user has the child node, so it didn't crop up yet.

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