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

Marek Vasut
2022-04-01T18:06:18Z

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. …