RE: [PATCH V2] dt-bindings: arm: fsl: Add DHCOM PicoITX and DHCOM DRC02 boards

[Christoph Niedermaier <cniedermaier@dh-electronics.com>]

From: Shawn Guo [mailto:shawnguo@kernel.org]
Sent: Wednesday, July 14, 2021 4:24 AM
> On Thu, Jul 08, 2021 at 07:38:44AM +0000, Christoph Niedermaier wrote:
>> From: Marek Vasut [mailto:marex@denx.de]
>> Sent: Wednesday, June 16, 2021 1:33 PM
>>
>>
>>> On 6/16/21 1:19 PM, Christoph Niedermaier wrote:
>>>> Send reply also to Rob Herrings +dt email address:
>>>>
>>>> From: Rob Herring <robh@kernel.org>
>>>> Sent: Wednesday, June 2, 2021 9:50 PM
>>>>
>>>>> On Tue, May 25, 2021 at 04:30:01PM +0200, Christoph Niedermaier wrote:
>>>>>> Add DH electronics DHCOM PicoITX and DHCOM DRC02 boards.
>>>>>>
>>>>>> Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
>>>>>> Cc: linux-arm-kernel@lists.infradead.org
>>>>>> Cc: linux-kernel@vger.kernel.org
>>>>>> Cc: robh+dt@kernel.org
>>>>>> Cc: Shawn Guo <shawnguo@kernel.org>
>>>>>> Cc: kernel@dh-electronics.com
>>>>>> To: devicetree@vger.kernel.org
>>>>>> ---
>>>>>> V2: Remove line with fsl,imx6s on the DRC02 Board
>>>>>> ---
>>>>>>   Documentation/devicetree/bindings/arm/fsl.yaml | 12 ++++++++++++
>>>>>>   1 file changed, 12 insertions(+)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/arm/fsl.yaml b/Documentation/devicetree/bindings/arm/fsl.yaml
>>>>>> index fce2a8670b49..3c4ff79a3be7 100644
>>>>>> --- a/Documentation/devicetree/bindings/arm/fsl.yaml
>>>>>> +++ b/Documentation/devicetree/bindings/arm/fsl.yaml
>>>>>> @@ -407,6 +407,12 @@ properties:
>>>>>>             - const: dfi,fs700e-m60
>>>>>>             - const: fsl,imx6dl
>>>>>>
>>>>>> +      - description: i.MX6DL DHCOM PicoITX Board
>>>>>> +        items:
>>>>>> +          - const: dh,imx6dl-dhcom-picoitx
>>>>>> +          - const: dh,imx6dl-dhcom-som
>>>>>> +          - const: fsl,imx6dl
>>>>>> +
>>>>>>         - description: i.MX6DL Gateworks Ventana Boards
>>>>>>           items:
>>>>>>             - enum:
>>>>>> @@ -458,6 +464,12 @@ properties:
>>>>>>             - const: toradex,colibri_imx6dl          # Colibri iMX6 Module
>>>>>>             - const: fsl,imx6dl
>>>>>>
>>>>>> +      - description: i.MX6S DHCOM DRC02 Board
>>>>>> +        items:
>>>>>> +          - const: dh,imx6s-dhcom-drc02
>>>>>> +          - const: dh,imx6s-dhcom-som
>>>>>> +          - const: fsl,imx6dl
>>>>>
>>>>> fsl,imx6s?
>>>>
>>>> In the first version I had here an additional line with "fsl,imx6s",
>>>> but currently the kernel isn't supporting that compatible. The i.MX6
>>>> Solo is currently supported by "fsl,imx6dl". So my idea was to add
>>>> both "fsl,imx6dl" and "fsl,imx6s" to match it maybe on a later kernel
>>>> version. If there is no match with the Solo now, it will fall back to
>>>> the i.MX6 DualLite. That is why I had both fsl,imx6s and fsl,imx6dl
>>>> in that order. On Fabio's advice, I removed the line with "fsl,imx6s"
>>>> in version 2.
>>>> Is this what you meant by your comment?
>>>
>>> I didn't notice that at first myself, but I think what Rob means is
>>>
>>> - const: dh,imx6s-dhcom-drc02
>>> - const: dh,imx6s-dhcom-som
>>> - const: fsl,imx6dl <------ this should be consistent with the two above
>>>
>>> that is
>>>
>>>   - const: dh,imx6s-dhcom-drc02
>>>   - const: dh,imx6s-dhcom-som
>>> -- const: fsl,imx6dl
>>> +- const: fsl,imx6s
>>>                ^^^^^
>>>
>>> But that is a bit odd here:
>>> - The MX6S is MX6DL with one CPU core disabled.
>>> - The DRC02 device can only house a SOM with MX6S and NOT with MX6DL
>>> (due to some thermal design consideration or something).
>>> - The kernel discerns the MX6S/MX6DL automatically based on the number
>>> of cores it reads from some register, therefore it only has the
>>> fsl,mx6dl compatible to cover both MX6S and MX6DL.
>>> So, the closest fallback compatible for this device really is the MX6DL,
>>> i.e. fsl,imx6dl.
>>>
>>> So I think this patch is correct as-is, no ?
>>
>> Is this Patch OK?
> 
> Can we explain that fsl,imx6s thing a bit with some comments or commit
> log?
> 
> Shawn

I will send a version 3.

Regards
Christoph