Re: [PATCH] dt-bindings: display: panel: Make DSI panels port optional

[Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>]

On 11/11/2026 13:37, Dmitry Baryshkov wrote:
> On Wed, Nov 11, 2026 at 01:31:39PM +0100, Krzysztof Kozlowski wrote:
>> On 11/11/2026 13:30, Krzysztof Kozlowski wrote:
>>> On 11/11/2026 12:13, Maxime Ripard wrote:
>>>> On Wed, Nov 11, 2026 at 12:03:39PM +0100, Krzysztof Kozlowski wrote:
>>>>> DSI panels can be placed under DSI bus directly and many Linux DRM
>>>>> drivers will work fine with it: mipi_dsi_host_register() adds device for
>>>>> such panel and DRM driver does not use OF graph to configure lanes.
>>>>
>>>> That's not true. We do use the endpoints to configure the lanes through
>>>> the data-lanes property. See drm_of_get_data_lanes*
>>>
>>> Some drivers use endpoints, some not. As discussed on other thread,
>>> there are more than which do not.
>>
>> "there are more than one which do not."
> 
> Which means that those should be fixed. We have legacy cases where the
> drivers assumed that, but we should not target legacy.

These legacy drivers work fine for 10 or 15 years, like Exynos.

You can improve them, for sure, but if no one does that then requiring a
graph is a mistake there, from the panel point of view.

...

>>>> DSI busses can handle multiple devices, and multiple data types. If we
>>>> were to drop the port node, how does the upstream video device know
>>>> which device it should send its video output to?
>>>>
>>>
>>> We do not drop the port node, who suggested that?
>>>
>>> You do get, that we are not talking about the DSI host, but the panel?
> 
> The panel might be driven by the host directly or there can be other
> chips on the bus (someboby has been asking about the retimer or
> something else sitting on the DSI bus between the host and the panel).

Sure, does not change that panel DOES NOT require the graph node.
Neither current Linux drivers, except some.

Best regards,
Krzysztof