linux-kernel - Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb

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Date:   Thu, 1 Dec 2016 18:15:46 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:     linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP
 patch bomb

Hi Boris,

2016-11-30 17:17 GMT+09:00 Boris Brezillon <boris.brezillon@...e-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