Re: [PATCH] dt-bindings: display: bridge: Drop requirement on input port for DSI devices

[Rob Herring <robh@kernel.org>]

On Fri, Apr 1, 2022 at 1:06 PM Marek Vasut <marex@denx.de> wrote:
>
> On 4/1/22 19:34, Rob Herring wrote:
> > On Fri, Apr 01, 2022 at 03:22:19AM +0200, Marek Vasut wrote:
> >> On 4/1/22 01:52, Rob Herring wrote:
> >>> On Wed, 23 Mar 2022 16:48:23 +0100, Maxime Ripard wrote:
> >>>> MIPI-DSI devices, if they are controlled through the bus itself, have to
> >>>> be described as a child node of the controller they are attached to.
> >>>>
> >>>> Thus, there's no requirement on the controller having an OF-Graph output
> >>>> port to model the data stream: it's assumed that it would go from the
> >>>> parent to the child.
> >>>>
> >>>> However, some bridges controlled through the DSI bus still require an
> >>>> input OF-Graph port, thus requiring a controller with an OF-Graph output
> >>>> port. This prevents those bridges from being used with the controllers
> >>>> that do not have one without any particular reason to.
> >>>>
> >>>> Let's drop that requirement.
> >>>>
> >>>> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> >>>> ---
> >>>>    .../devicetree/bindings/display/bridge/chipone,icn6211.yaml      | 1 -
> >>>>    .../devicetree/bindings/display/bridge/toshiba,tc358762.yaml     | 1 -
> >>>>    2 files changed, 2 deletions(-)
> >>>>
> >>>
> >>> I tend to agree with port@0 not being needed and really like
> >>> consistency.
> >>
> >> The consistent thing to do would be to always use port@0 and OF graph, no ?
> >
> > I guess it depends how wide our scope for consistency is. Just DSI bus
> > controlled bridges? DSI panels? All bridges and panels? Any panel
> > without a control interface has the same dilemma as those can be a child
> > of the display controller (or bridge) and not even use OF graph.
>
> I would likely opt for the OF graph in all cases, panels, bridges,
> controllers. Then it would be consistent.
>
> > All simple panels don't require 'port' either. That's presumably only
> > consistent because we made a single schema. I'd assume 'non-simple'
> > panels with their own schema are not consistent.
>
> Maybe we would start requiring that port even for simple panels ?
> The port is physically there on that panel after all.

Fix this in all the dts files and then I'll agree. Though I think this
ship has already sailed. I'd like to someday get to platforms without
warnings and not just keep adding new warnings.

Rob