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

[Marek Vasut]

On 10/7/20 3:33 PM, Laurent Pinchart wrote:
> Hi Marek,
> 
> On Wed, Oct 07, 2020 at 10:55:24AM +0200, Marek Vasut wrote:
>> 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" ?
> 
> Nothing, until the next patch :-) This patch only handles the YAML
> conversion but doesn't fix issues.

Good, thanks !