linux-kernel - Re: [PATCH] Add support for Macronix NAND randomizer

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Message-ID: <20190824130329.68f310aa@xps13>
Date:   Sat, 24 Aug 2019 13:03:29 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Mason Yang <masonccyang@...c.com.tw>
Cc:     richard@....at, marek.vasut@...il.com, dwmw2@...radead.org,
        bbrezillon@...nel.org, computersforpeace@...il.com,
        vigneshr@...com, kstewart@...uxfoundation.org,
        juliensu@...c.com.tw, linux-kernel@...r.kernel.org,
        frieder.schrempf@...tron.de, linux-mtd@...ts.infradead.org,
        tglx@...utronix.de
Subject: Re: [PATCH] Add support for Macronix NAND randomizer

Hi Mason,

Mason Yang <masonccyang@...c.com.tw> wrote on Tue, 20 Aug 2019 13:53:48
+0800:

> Macronix NANDs support randomizer operation for user data scrambled,
> which can be enabled with a SET_FEATURE.
> 
> User data written to the NAND device without randomizer is still readable
> after randomizer function enabled.
> The penalty of randomizer are NOP = 1 instead of NOP = 4 and more time period

please don't use 'NOP' here, use 'subpage accesses' instead, otherwise
people might not understand what it means while it has a real impact.

> is needed in program operation and entering deep power-down mode.
> i.e., tPROG 300us to 340us(randomizer enabled)
> 
> If subpage write not available with hardware ECC, for example,
> NAND chip options NAND_NO_SUBPAGE_WRITE be set in driver and
> randomizer function is recommended for high-reliability.
> Driver checks byte 167 of Vendor Blocks in ONFI parameter page table
> to see if this high-reliability function is supported.
> 

You did not flagged this patch as a v2 and forgot about the changelog.
You did not listen to our comments in the last version neither. I was
open to a solution with a specific DT property for warned users but I
don't see it coming.
 

Thanks,
Miquèl