[PATCH v2 1/7] dt-bindings: display: mxsfb: Convert binding to YAML

[Marek Vasut]

On 10/7/20 10:43 AM, Lucas Stach wrote:
> On Mi, 2020-10-07 at 10:32 +0200, Marek Vasut wrote:
>> On 10/7/20 3:24 AM, Laurent Pinchart wrote:
>> [...]
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - fsl,imx23-lcdif
>>> +      - fsl,imx28-lcdif
>>> +      - fsl,imx6sx-lcdif
>>> +      - fsl,imx8mq-lcdif
>>
>> There is no fsl,imx8mq-lcdif in drivers/gpu/drm/mxsfb/mxsfb_drv.c,
>> so the DT must specify compatible = "fsl,imx8mq-lcdif",
>> "fsl,imx28-lcdif" (since imx28 is the oldest SoC with LCDIF V4).
>>
>> Should the compatible be added to drivers/gpu/drm/mxsfb/mxsfb_drv.c or
>> dropped from the YAML file or neither ?
> 
> Neither. As far as we know the block is compatible, so the DT should
> claim that it's compatible to "fsl,imx28-lcdif". However we don't know
> if there are any surprises, so we add the SoC specific compatible to be
> able to change the driver matching later without changing the DT if the
> need arises. For the DT validation to pass the SoC specific compatible 
> needs to be documented, even if it currently unused by the driver.

What in that binding says you should specify compatible =
"fsl,imx8mq-lcdif", "fsl,imx28-lcdif"; and not e.g. "fsl,imx8mq-lcdif",
"fsl,imx23-lcdif" or simply "fsl,imx8mq-lcdif" ?