Re: [PATCH v8 1/9] dt-bindings: display: fsl,ldb: Add i.MX94 LDB

Marek Vasut
2026-03-20T03:59:09Z

On 3/19/26 9:57 AM, Laurentiu Palcu wrote:
> On Fri, Mar 06, 2026 at 09:46:57AM +0100, Marco Felsch wrote:
>> On 26-03-06, Liu Ying wrote:
>>> On Wed, Mar 04, 2026 at 11:34:10AM +0000, Laurentiu Palcu wrote:
>>>> i.MX94 has a single LVDS port and share similar LDB and LVDS control
>>>> registers as i.MX8MP and i.MX93.
>>>>
>>>> Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
>>>> Reviewed-by: Frank Li <Frank.Li@nxp.com>
>>>> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> ---
>>>> Documentation/devicetree/bindings/display/bridge/fsl,ldb.yaml | 2 ++
>>>> 1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/display/bridge/fsl,ldb.yaml b/Documentation/devicetree/bindings/display/bridge/fsl,ldb.yaml
>>>> index 7f380879fffdf..fb70409161fc0 100644
>>>> --- a/Documentation/devicetree/bindings/display/bridge/fsl,ldb.yaml
>>>> +++ b/Documentation/devicetree/bindings/display/bridge/fsl,ldb.yaml
>>>> @@ -20,6 +20,7 @@ properties:
>>>> - fsl,imx6sx-ldb
>>>> - fsl,imx8mp-ldb
>>>> - fsl,imx93-ldb
>>>> + - fsl,imx94-ldb
>>>
>>> Cc'ing Marco.
>>>
>>> Recently, Marco said that LDB node should not have a reg property...
>>>
>>> https://lore.kernel.org/all/4sofljffovrorpxe2os3jl745qfjoglvl54oqf3v7r5bk5f6aq@6y3jwn4abiqy/
>>
>> Yes, this has to be dropped. All variants of this specific "IP" use the
>> same approach. This "IP" is part of a general purpose register layout
>> with very loose reg-field definitions: e.g. resets and clk-gatting share
>> the same register. Or a mux reg-field shares the same register as a
>> MIPI-{C,D}SI configuration reg-field. Therefore this "IP" is part of a
>> syscon and should be abstracted as such within the DT.
>
> Even though I understand the logic behind why 'reg' should be dropped,
> I'm not exactly sure how to proceed with this. It appears Marek made the
> 'reg' required in this commit (merely 2 months ago):
>
> 8aa2f0ac08d3b - dt-bindings: display: bridge: ldb: Add check for reg and reg-names
>
> Should the above patch simply be reverted and have 'reg' as optional again?
> Or should the 'reg' and 'reg-names' be removed completely from the
> binding.
>
> @Marek, any comments?
The LDB driver was always written with parsing 'reg' out of the DT, so
encoding the register offsets into the driver was a mistake. The LDB
controls two registers, which can be comfortably described in DT.