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From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Thu, 1 Dec 2016 18:15:46 +0900
Message-ID: <CAK7LNAQO7dKxFYcTJ+S6sQTPJCK98820_x3y82gfSjk0e4NeFw@mail.gmail.com>
Subject: Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP
 patch bomb
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Marek Vasut <marek.vasut@gmail.com>,
        Brian Norris <computersforpeace@gmail.com>,
        Richard Weinberger <richard@nod.at>,
        David Woodhouse <dwmw2@infradead.org>,
        Cyrille Pitchen <cyrille.pitchen@atmel.com>,
        Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Hi Boris,

2016-11-30 17:17 GMT+09:00 Boris Brezillon <boris.brezillon@free-electrons.com>:

>> [3]
>> Fix raw and oob callbacks.
>>
>> I asked in another thread,
>> the current driver just puts the physically accessed OOB data
>> into oob_poi, which is not a collection of ECC data.
>> Raw write/read() are wrong as well.
>
> That's all good things too.
>
>>
>> After fixing those, enable BBT scan by removing the following flag:
>>     /* skip the scan for now until we have OOB read and write support */
>>     chip->options |= NAND_SKIP_BBTSCAN;
>>
>
> Hm, here you have a problem. The layout you described replaces BBMs by
> payload data, thus preventing the BBM scan approach (or at least, it
> won't work with factory BBMs).


As I answered in another mail, the Denali IP expects BBMs
at the beginning of each OOB area (standard location).
They are protected from the ECC engine.

I just did not mention the BBM-reserved area
to make the story simpler.

So, after fixing oob read/write functions,
the driver will be able to enable BBT-scanning.


-- 
Best Regards
Masahiro Yamada