Re: [PATCH v2 1/2] dt-bindings: drm/bridge: Add no-hpd property

[Jayesh Choudhary]

On 06/04/23 07:10, Laurent Pinchart wrote:
> Hi Jayesh,
>
> Thank you for the patch.
>
> On Wed, Apr 05, 2023 at 07:54:39PM +0530, Jayesh Choudhary wrote:
> > From: Rahul T R <r-ravikumar@xxxxxx>
> >
> > The mhdp bridge can work without its HPD pin hooked up to the connector,
> > but the current bridge driver throws an error when hpd line is not
> > connected to the connector. For such cases, we need an indication for
> > no-hpd, using which we can bypass the hpd detection and instead use the
> > auxiliary channels connected to the DP connector to confirm the
> > connection.
> > So add no-hpd property to the bindings, to disable hpd when not
> > connected or unusable.
> >
> > Signed-off-by: Rahul T R <r-ravikumar@xxxxxx>
> > Signed-off-by: Jayesh Choudhary <j-choudhary@xxxxxx>
> > ---
> >   .../devicetree/bindings/display/bridge/cdns,mhdp8546.yaml   | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
> > index c2b369456e4e..3a6c6d837593 100644
> > --- a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
> > +++ b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
> > @@ -57,6 +57,12 @@ properties:
> >     interrupts:
> >       maxItems: 1
> >   
> > +  cdns,no-hpd:
> > +    type: boolean
> > +    description:
> > +      Set if the HPD line on the bridge isn't hooked up to anything or is
> > +      otherwise unusable.
>
> I'm fine with the non connected part, but concerned with "otherwise
> unusable". It's very vague and could thus be abused. Do you have
> particular use cases in mind for this ? If so, restricting this to those
> use cases, or at least giving examples, would help.

Okay. Will do that in next version.

Thanks.

> > +
> >     ports:
> >       $ref: /schemas/graph.yaml#/properties/ports
> >