Re: [PATCH v22 17/18] dt-bindings: mtd: pl353-nand: Describe this hardware controller

From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>,
	Rob Herring <robh+dt@kernel.org>
Cc: Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
	Michal Simek <monstr@monstr.eu>,
	Naga Sureshkumar Relli <nagasure@xilinx.com>,
	Amit Kumar Mahapatra <akumarma@xilinx.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, helmut.grohne@intenta.de,
	Srinivas Goud <sgoud@xilinx.com>,
	Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Subject: Re: [PATCH v22 17/18] dt-bindings: mtd: pl353-nand: Describe this hardware controller
Date: Wed, 9 Jun 2021 15:57:05 +0200	[thread overview]
Message-ID: <6fb9c0e4-43cb-d224-0ebe-568f62ac35b1@canonical.com> (raw)
In-Reply-To: <20210609153621.1303bc4d@xps13>

On 09/06/2021 15:36, Miquel Raynal wrote:
> Hi Krzysztof,
> 
> Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> wrote on Wed, 9
> Jun 2021 14:01:10 +0200:
> 
>> On 09/06/2021 10:01, Miquel Raynal wrote:
>>> Add a yaml description of this NAND controller which is described as a
>>> subnode of the SMC bus.
>>>
>>> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
>>> ---
>>>  .../bindings/mtd/arm,pl353-nand-r2p1.yaml     | 57 +++++++++++++++++++
>>>  1 file changed, 57 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/mtd/arm,pl353-nand-r2p1.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/mtd/arm,pl353-nand-r2p1.yaml b/Documentation/devicetree/bindings/mtd/arm,pl353-nand-r2p1.yaml
>>> new file mode 100644
>>> index 000000000000..e72fa14b4385
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/mtd/arm,pl353-nand-r2p1.yaml
>>> @@ -0,0 +1,57 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/mtd/arm,pl353-nand-r2p1.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: PL353 NAND Controller device tree bindings
>>> +
>>> +allOf:
>>> +  - $ref: "nand-controller.yaml"
>>> +
>>> +maintainers:
>>> +  - Miquel Raynal <miquel.raynal@bootlin.com>
>>> +  - Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    items:
>>> +      - enum:  
>>
>> That's not an enum, but simple const without items.
> 
> Ok.
> 
>>
>>> +          - arm,pl353-nand-r2p1
>>> +
>>> +  reg:
>>> +    items:
>>> +      - items:
>>> +          - description: CS with regard to the parent ranges property
>>> +          - description: Offset of the memory region requested by the device
>>> +          - description: Length of the memory region requested by the device  
>>
>> Doesn't it depend on parent's address/size cells?
> 
> Yes, but as the child nodes are not defined in the parent's binding
> (ie. the SMC) I think it's interesting to have them defined here, no?

The trouble is if parent decides to have different address/size cells.
The schema will stop matching. I am actually not that sure if such case
is real since the pl353 NAND part will usually be connected to pl353
SMC. However the schema now hard-codes specific dependency against
parent schema/node.

Rob,
Maybe you have here some thoughts?

Best regards,
Krzysztof