Re: [PATCH] dt-bindings: display: bridge: ldb: Require reg property only for i.MX6SX/8MP LDBs

[Marek Vasut <marex@nabladev.com>]

On 3/30/26 8:29 AM, Marco Felsch wrote:

Hello Marco,

>>> On 26-03-29, Liu Ying wrote:
>>>> LDB's parent device could be a syscon which doesn't allow a reg property
>>>> to be present in it's child devices, e.g., NXP i.MX93 Media blk-ctrl
>>>> has a child device NXP i.MX93 Parallel Display Format Configuration(PDFC)
>>>> without a reg property(LDB is also a child device of the Media blk-ctrl).
>>>> To make the LDB schema be able to describe LDBs without the reg property
>>>> like i.MX93 LDB, require the reg property only for i.MX6SX/8MP LDBs.
>>>
>>> NACK, we want to describe the HW and from HW PoV the LDB is and was
>>> always part of a syscon. This is the case for all SoCs i.MX6SX/8MP/93.
>>>
>>>> Fixes: 8aa2f0ac08d3 ("dt-bindings: display: bridge: ldb: Add check for reg and reg-names")
>>>
>>> Therefore I would just revert this patch completely.
>> Last time, I pointed out the hardware is part of syscon, but as a subnode
>> and therefore with reg properties. What is the problem there ?
> 
> To quote the DT spec here:
> 
> """
> The reg property describes the address of the device’s resources within
> the address space defined by its parent bus.
> """

That parent bus would be the syscon, wouldn't it.

> The parent bus is not the parent iomuxc (i.MX6X) nor the blk-ctrl
> (i.MX8MP/93) device. Therefore this is wrong IMHO and should be dropped.

How so ? What is the parent bus ?