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Date:   Thu, 24 May 2018 14:19:18 +0200
From:   Stefan Agner <stefan@agner.ch>
To:     Boris Brezillon <boris.brezillon@bootlin.com>
Cc:     Benjamin Lindqvist <benjamin.lindqvist@endian.se>,
        dwmw2@infradead.org, computersforpeace@gmail.com,
        marek.vasut@gmail.com, robh+dt@kernel.org, mark.rutland@arm.com,
        thierry.reding@gmail.com, mturquette@baylibre.com,
        sboyd@kernel.org, Lucas Stach <dev@lynxeye.de>,
        miquel.raynal@bootlin.com, richard@nod.at, marcel@ziswiler.com,
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        pdeschrijver@nvidia.com, pgaikwad@nvidia.com,
        Mirza Krak <mirza.krak@gmail.com>,
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        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-clk@vger.kernel.org
Subject: Re: [RESEND PATCH 2/5] mtd: rawnand: add NVIDIA Tegra NAND Flash
 controller driver
In-Reply-To: <20180524135335.6aa0b7a4@bbrezillon>
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On 24.05.2018 13:53, Boris Brezillon wrote:
> Hi Benjamin,
> 
> On Thu, 24 May 2018 13:30:14 +0200
> Benjamin Lindqvist <benjamin.lindqvist@endian.se> wrote:
> 
>> Hi Stefan,
>>
>> It seems to me that a probe similar to what the BootROM does shouldn't
>> be awfully complicated to implement - just cycle through the switch
>> cases in case of an ECC error. But I guess that's more of an idea for
>> further improvements rather than a comment to the patch set under
>> review.
> 
> Nope, not really an option, because you're not guaranteed that the NAND
> will be used as a boot media, and the first page or first set of pages
> might just be erased.
> 

Yeah I did not meant probing like the Boot ROM does.

What I meant was using only the ECC modes which are supported by the
Boot ROM when the driver tries to choose a viable mode. So that would
be:
- RS t=4
- BCH t=8
- BCH t=16

Maybe we could add a property to enable that behavior:

tegra,use-bootable-ecc-only;

>>
>> However, I think that allowing for an override of the oobsize
>> inference would be a good idea before merging, no? This could just be
>> a trivial #ifdef (at least temporarily). If you agree but don't feel
>> like doing it yourself, I'd be happy to pitch in. Let me know.
> 
> That's why we have nand-ecc-xxx properties in the DT.
> 

Yes, nand-ecc-strength is the first thing I plan to implement, that way
strength can be defined in dt.

--
Stefan