linux-kernel - Re: [PATCH 01/21] mtd: spinand: Use more specific naming for the reset op

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Message-ID: <f1111d1b-a111-4171-9467-450d90a14c0a@linaro.org>
Date: Mon, 10 Mar 2025 12:14:06 +0200
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Richard Weinberger <richard@....at>, Vignesh Raghavendra
 <vigneshr@...com>, Santhosh Kumar K <s-k6@...com>,
 Pratyush Yadav <pratyush@...nel.org>, Michael Walle <michael@...le.cc>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Steam Lin <stlin2@...bond.com>, linux-mtd@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/21] mtd: spinand: Use more specific naming for the
 reset op

On 07.03.2025 17:45, Miquel Raynal wrote:
> Hi Tudor,

Hi!

> 
>>> -#define SPINAND_RESET_OP						\
>>> +#define SPINAND_RESET_1S_0_0_OP						\
>> Hi, Miquel,
>>
>> Have you seen any reset op with address or data? If not, I'm not really
>> sure whether we shall change the name for these basic operations.
>>
>> Changing them to 1S-0-0 may also indicate that there are resets with
>> address or data fields, which I find confusing.
>>
>> I think the change is good for reads and writes. I'll check further in
>> the series and let you know.
> 
> I want to rename this macro for two reasons:
> - We might see in the near future the addition of 8D-0-0 ops (I plan on
>   working on it).
> - I would like some kind of harmony among these macros.
> 
> Now, whether is should be named like I proposed or just
> SPINAND_RESET_OP_1S, I have no strong preference and I can change that
> in an upcoming version.
> 
> Which one would you prefer?

I don't know. Which one is backed up by a standard?

JESD216F defines
"(An-Bn-Cn): Command mode nomenclature used to indicate the number of
active pins used for the instruction (A), address (B), and data (C), and
the data rate used for each. Data rates(n) can be single (S) and dual (D)."

Also, "(x-y-z) nomenclature is equivalent to(AS-BS-CS) unless otherwise
noted."

What's an "active pin"?

Then if I look at JESD251-1.01 and JESD251C, (An-Bn-Cn) is referred to
as "protocol mode". Write Enable, which is just an instruction command
with no address or data, is seen as a required command in both 4D-4D-4D
and 8D-8D-8D protocol modes, and it's defined as a "1.A" transaction
format command. And the transaction format is:
'''
The following transaction formats are used in Profile 1.0 mode 8D-8D-8D:
Format 1.A: Command and Command Extension
Format 1.B: Command, Command Extension, 4-byte Address, ‘n’ Latency
Cycles, and Read Data
Format 1.C: Command, Command Extension, and 4-byte Address
Format 1.D: Command, Command Extension, 4-byte Address, and Write Data
'''

So according to these standards maybe we shall refer to it as:
WREN-8D-8D-8D-1A? This seems less intuitive than 8D-0-0, but I think it
all depends on what's an "active pin". I think it describes the protocol
mode, and not what's actually sent on the line. As we saw, WREN is
considered an 8D-8D-8D command, and not an 8D-0-0 command.

For dual mode, which is not covered by xSPI, I guess we can use the
single spi transaction formats 0.{A,B,C,...}.

How do you feel about a OP-An-Bn-Cn-transaction-format,
	where A, B, C is {1, 2, 4, 8}
	n is {S, D}
	transaction format is {0,1,2,3}{A,B,C,...}

Care must be taken care of at the transaction format, as I see there are
a few, depending on the xSPI profile and protocol mode.

Cheers,
ta