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Date:   Tue, 10 Jul 2018 14:17:15 +0200
From:   Boris Brezillon <boris.brezillon@bootlin.com>
To:     "Bean Huo (beanhuo)" <beanhuo@micron.com>
Cc:     Chris Packham <chris.packham@alliedtelesis.co.nz>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
        "miquel.raynal@bootlin.com" <miquel.raynal@bootlin.com>,
        "computersforpeace@gmail.com" <computersforpeace@gmail.com>,
        "dwmw2@infradead.org" <dwmw2@infradead.org>
Subject: Re: [PATCH v6 0/6] mtd: rawnand: support MT29F1G08ABAFAWP-ITE:F
Message-ID: <20180710141715.375ac6df@bbrezillon>
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On Tue, 10 Jul 2018 11:40:08 +0000
"Bean Huo (beanhuo)" <beanhuo@micron.com> wrote:

> Hi,  Boris
> >>
> >> Okay, I think we already had this discussion, but I'm asking it again.
> >> What are the possible values for that field and what do they mean?  
> >
> >Still, it's not clear to me what "Internal ECC level" means. It seems that NAND
> >chips having on-die ECC have this field set to 10b (0x2), 00b seems to be
> >reserved for "no on-die ECC", but what are 01b and 11b reserved for?
> >  
> 
> That position identifies the part as having Internal ECC capability.  
> The 01b and 11b are reserved for future definition.  Bit 7 of READ ID Byte 4 identifies the
> device as an ECC OFF 0x0 or ECC ON 0x1.
> 
> >> Also, is it even used to encode the fact that the NAND has on-die ECC
> >> on all your NANDs? We already had the problem of incompatible ID
> >> schemes, so I wouldn't be surprised if that was the case here, hence
> >> my initial suggestion to base the detection on the model name.  
> >
> >I'd really need to have an answer on that one to take a decision. Also, I
> >couldn't find a datasheet for an IT (without E) version of the
> >MT29F1G08ABAFAWP part. Does it exist, or can we assume
> >MT29F1G08ABAFAWP chips always come with forcibly enabled on-die ECC?  
> 
> MT29F1G08ABAFAWP comes in ECC ON only.  We didn’t develop a
> MT29F1G08ABAFAWP ECC OFF version.  Bit 7 of READ ID Byte 4 identifies the
> device as an ECC OFF 0x0 or ECC ON 0x1.
> 

Okay. Can you have a look at the patches I sent an let me know if I do
the right thing?