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

[Shawn Guo <shawnguo@kernel.org>]

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