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

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Conor,

Am Dienstag, 24. Oktober 2023, 11:08:56 CET schrieb Conor Dooley:
> On Tue, Oct 24, 2023 at 08:30:16AM +0200, Alexander Stein wrote:
> > Am Montag, 23. Oktober 2023, 18:37:29 CEST schrieb Conor Dooley:
> > > 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-ct
> > > > > > rl.y
> > > > > > aml
> > > > > > b/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ct
> > > > > > rl.y
> > > > > > aml
> > > > > > index b3554e7f9e76..5ba66dfb0e05 100644
> > > > > > ---
> > > > > > a/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ct
> > > > > > rl.y
> > > > > > aml
> > > > > > +++
> > > > > > b/Documentation/devicetree/bindings/soc/imx/fsl,imx93-media-blk-ct
> > > > > > rl.y
> > > > > > aml>
> > > > > > 
> > > > > > @@ -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.ya
> > > > ml
> > > > 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.
> > 
> > I was not able to raise a warning with enabled media_blk_ctrl having
> > #address- cells/#size-cells being set but no subnode.
> > I don't have a strong opinion on this, but I prefer having both bindings
> > as
> > similar as possible.
> 
> The complaint is from dtc, possibly only at W=1:
> unnecessary #address-cells/#size-cells without "ranges" or child "reg"
> property

I was still not able to trigger this. But anyway this binding is for i.MX93 
MEDIAMIX Block Control. There is exactly one of this instance in the SoC. So 
there is always the LVDS bridge included, thus the ldb subnode shall be added.
Given this IMHO #address-cells/#size-cells can be required.

Best regards,
Alexander
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