Re: [PATCH v5 08/31] dt-bindings: soc: fsl: cpm_qe: cpm1-scc-qmc: Add support for QMC HDLC

[Herve Codina <herve.codina@xxxxxxxxxxx>]

Hi Conor,

On Tue, 12 Sep 2023 18:21:58 +0100
Conor Dooley <conor@xxxxxxxxxx> wrote:

> On Tue, Sep 12, 2023 at 12:10:18PM +0200, Herve Codina wrote:
> > The QMC (QUICC mutichannel controller) is a controller present in some
> > PowerQUICC SoC such as MPC885.
> > The QMC HDLC uses the QMC controller to transfer HDLC data.
> > 
> > Additionally, a framer can be connected to the QMC HDLC.
> > If present, this framer is the interface between the TDM bus used by the
> > QMC HDLC and the E1/T1 line.
> > The QMC HDLC can use this framer to get information about the E1/T1 line
> > and configure the E1/T1 line.
> > 
> > Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> > ---
> >  .../bindings/soc/fsl/cpm_qe/fsl,cpm1-scc-qmc.yaml   | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/soc/fsl/cpm_qe/fsl,cpm1-scc-qmc.yaml b/Documentation/devicetree/bindings/soc/fsl/cpm_qe/fsl,cpm1-scc-qmc.yaml
> > index 82d9beb48e00..b5073531f3f1 100644
> > --- a/Documentation/devicetree/bindings/soc/fsl/cpm_qe/fsl,cpm1-scc-qmc.yaml
> > +++ b/Documentation/devicetree/bindings/soc/fsl/cpm_qe/fsl,cpm1-scc-qmc.yaml
> > @@ -101,6 +101,16 @@ patternProperties:
> >            Channel assigned Rx time-slots within the Rx time-slots routed by the
> >            TSA to this cell.
> >  
> > +      compatible:
> > +        const: fsl,qmc-hdlc
> > +
> > +      fsl,framer:
> > +        $ref: /schemas/types.yaml#/definitions/phandle
> > +        description:
> > +          phandle to the framer node. The framer is in charge of an E1/T1 line
> > +          interface connected to the TDM bus. It can be used to get the E1/T1 line
> > +          status such as link up/down.  
> 
> Sounds like this fsl,framer property should depend on the compatible
> being present, no?

Well from the implementation point of view, only the QMC HDLC driver uses this
property.

>From the hardware description point of view, this property means that the time slots
handled by this channel are connected to the framer. So I think it makes sense for
any channel no matter the compatible (even if compatible is not present).

Should I change and constraint the fsl,framer property to the compatible presence ?
If so, is the following correct for this contraint ?
   --- 8< ---
   dependencies:
     - fsl,framer: [ compatible ];
   --- 8< ---

Regards,
Hervé

> 
> Thanks,
> Conor.
> 
> > +
> >      required:
> >        - reg
> >        - fsl,tx-ts-mask
> > @@ -159,5 +169,8 @@ examples:
> >              fsl,operational-mode = "hdlc";
> >              fsl,tx-ts-mask = <0x00000000 0x0000ff00>;
> >              fsl,rx-ts-mask = <0x00000000 0x0000ff00>;
> > +
> > +            compatible = "fsl,qmc-hdlc";
> > +            fsl,framer = <&framer>;
> >          };
> >      };
> > -- 
> > 2.41.0
> >