linux-kernel - Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nand: Convert to DT schema format

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Date:   Tue, 21 Sep 2021 19:12:49 +0530
From:   Apurva Nandan <a-nandan@...com>
To:     Rob Herring <robh@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>
CC:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        <linux-mtd@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <michael@...le.cc>
Subject: Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nand: Convert to DT schema
 format

Hi Rob,

On 21/09/21 2:46 am, Rob Herring wrote:
> On Mon, Sep 20, 2021 at 06:06:51PM +0300, Serge Semin wrote:
>> Hello Apurva
>>
>> On Mon, Sep 20, 2021 at 07:57:12PM +0530, Apurva Nandan wrote:
>>> Convert spi-nand.txt binding to YAML format with an added example.
>>>
>>> Signed-off-by: Apurva Nandan <a-nandan@...com>
>>> ---
>>>   .../devicetree/bindings/mtd/spi-nand.txt      |  5 --
>>>   .../devicetree/bindings/mtd/spi-nand.yaml     | 62 +++++++++++++++++++
>>>   2 files changed, 62 insertions(+), 5 deletions(-)
>>>   delete mode 100644 Documentation/devicetree/bindings/mtd/spi-nand.txt
>>>   create mode 100644 Documentation/devicetree/bindings/mtd/spi-nand.yaml
>> Thanks for the bindings conversion patch. There are several comments
>> below. But before addressing them it would be better to also get a
>> response from Rob.
>>
>>> diff --git a/Documentation/devicetree/bindings/mtd/spi-nand.txt b/Documentation/devicetree/bindings/mtd/spi-nand.txt
>>> deleted file mode 100644
>>> index 8b51f3b6d55c..000000000000
>>> --- a/Documentation/devicetree/bindings/mtd/spi-nand.txt
>>> +++ /dev/null
>>> @@ -1,5 +0,0 @@
>>> -SPI NAND flash
>>> -
>>> -Required properties:
>>> -- compatible: should be "spi-nand"
>>> -- reg: should encode the chip-select line used to access the NAND chip
>>> diff --git a/Documentation/devicetree/bindings/mtd/spi-nand.yaml b/Documentation/devicetree/bindings/mtd/spi-nand.yaml
>>> new file mode 100644
>>> index 000000000000..601beba8d971
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/mtd/spi-nand.yaml
>>> @@ -0,0 +1,62 @@
>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/mtd/spi-nand.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: SPI NAND flash
>>> +
>>> +maintainers:
>>> +  - Apurva Nandan <a-nandan@...com>
>>> +
>>> +allOf:
>>> +  - $ref: "mtd.yaml#"
>>> +
>>> +properties:
>>> +  compatible:
>>> +    const: spi-nand
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  spi-max-frequency: true
>>> +  spi-rx-bus-width: true
>>> +  spi-tx-bus-width: true
>>> +  rx-sample-delay-ns: true
>> Since it's an SPI-client device there are more than these properties
>> could be set for it. See the SPI-controller bindings schema:
>> Documentation/devicetree/bindings/spi/spi-controller.yaml
>> So there is two possible ways to make it more generic:
>> 1) Detach the spi-client part from the spi-controller.yaml bindings
>> into a dedicated DT-schema file and refer to that new scheme from
>> here.
> Yes, as mentioned there's patches doing this. But the above is fine.
> There's some value in defining here which properties are valid.
Yeah right
>> 2) Forget about these controller-specific properties and let the
>> parental SPI-controller bindings parsing them. Of course there must be
>> at least one of the next properties declared for it to work:
>> {unevaluatedProperties, additionalProperties}.
>>
>> It's up to Rob to decided which approach is better though...
>>
>>> +
>>> +  '#address-cells': true
>>> +  '#size-cells': true
>> Aren't they always equal to 1?
> No SPI nand devices >4GB?
Yeah, we have SPI NANDs >4GB, and "'#address-cells': true" allows those 
sizes.
>
>>> +
>>> +additionalProperties:
>>> +  type: object
>> I'd suggest to elaborate the way the partition sub-nodes looks
>> like, for instance, the node names, supported compatible names,
>> labels, etc.
> That should probably all be in mtd.yaml. The question here is whether
> partitions are always under a 'partitions' node. Maybe this is new
> enough that only the new way has to be supported. Though if mtd.yaml
> supported both forms, allowing both all the time is okay IMO.
>
> Rob

I had added the "partition" node properties in the v1 patch, but as per 
the reviews I removed it.
I think we can prefer having them in mtd.yaml if needed, in a separate 
patch series.
Do you prefer the mtd.yaml changes as a part of this series or as a 
separate patch?

Other than that, I don't find any need for a v3 patch re-roll, do you agree?

Thanks,
Apurva Nandan