linux-kernel - Re: [PATCH v5 3/5] dt-bindings: mtd: spi-nor: add OTP parameters

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Message-ID: <bcb4fcf5-b49b-4e1c-a5c4-e417d04097f0@kernel.org>
Date: Mon, 23 Sep 2024 17:42:36 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Erez <erezgeva2@...il.com>
Cc: Erez Geva <erezgeva@...ime.org>, linux-mtd@...ts.infradead.org,
 Tudor Ambarus <tudor.ambarus@...aro.org>,
 Pratyush Yadav <pratyush@...nel.org>, Michael Walle <mwalle@...nel.org>,
 linux-kernel@...r.kernel.org, Miquel Raynal <miquel.raynal@...tlin.com>,
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>,
 devicetree@...r.kernel.org, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Esben Haabendal <esben@...nix.com>
Subject: Re: [PATCH v5 3/5] dt-bindings: mtd: spi-nor: add OTP parameters

On 23/09/2024 11:21, Erez wrote:
> On Sun, 22 Sept 2024 at 22:40, Krzysztof Kozlowski <krzk@...nel.org> wrote:
>>
>> On Fri, Sep 20, 2024 at 08:12:29PM +0200, Erez Geva wrote:
>>> From: Erez Geva <ErezGeva2@...il.com>
>>>
>>> Some flash devices need OTP parameters in device tree.
>>> As we can not deduce the parameters based on JEDEC ID or SFDP.
>>>
>>> Signed-off-by: Erez Geva <ErezGeva2@...il.com>
>>> ---
>>>  .../bindings/mtd/jedec,spi-nor.yaml           | 39 +++++++++++++++++++
>>>  1 file changed, 39 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
>>> index 6e3afb42926e..4f7bb3f41cb1 100644
>>> --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
>>> +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
>>> @@ -90,6 +90,43 @@ properties:
>>>        the SRWD bit while writing the status register. WP# signal hard strapped to GND
>>>        can be a valid use case.
>>>
>>> +  otp-n-regions:
>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    description:
>>> +      Some flash devices need OTP parameters in the device tree.
>>> +      As we can not deduce the parameters based on JEDEC ID or SFDP.
>>> +      This parameter indicates the number of OTP regions.
>>
>> OTP regions where? In DTS? On flash itself?
> 
> Where can OTP regions be?
> Can you please be serious?
> If you have any suggestions, I am happy to hear.
> I did ask before.

Yes, I am serious, imagine that we do not know what you wanted to say.
At first this just sounded like you mix nvmem-cells here.

Out of blue this binding starts mentioning OTP and you add bunch of
generic properties not really matching anything so far. Instead of being
sarcastic about reviewers confusion, rather improve your description.

Otherwise, good luck.



> 
>>
>>> +      The value must be larger or equal to 1 and mandatory for OTP.
>>
>> Don't repeat constraints in free form text. Add proper minimum and
> 
> Sure, I will add a minimum.
> 
>> default, although it is confusing - property is not required but it is
>> mandatory for OTP?
> 
> You are welcome to suggest a better rephrase.
> Using OTP settings is optional.
> If you set OTP then the number of regions and region length are mandatory.
> While offset and base are optional for OTP settings.

So properties should be required?

> 
> 
>>
>>
>>
>>> +
>>> +  otp-len:
>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    description:
>>> +      Some flash devices need OTP parameters in the device tree.
>>> +      As we can not deduce the parameters based on JEDEC ID or SFDP.
>>
>> Don't repeat the same.
> 
> Is there a grouping description?
> 
>>
>>> +      This parameter indicates the size (length) in bytes of an OTP region.
>>
>> What if each region has different length? Is it possible?
> 
> Yes, there are. Old Mactronix have chips with the first region bigger
> than the second region.
> As these are old chips, we may skip the support of them.

Other devices can come later re-introducing this approach.



Best regards,
Krzysztof