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From: Paul Cercueil <paul@crapouillou.net>
To: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
David Woodhouse <dwmw2@infradead.org>,
linux-mtd@lists.infradead.org, Rob Herring <robh+dt@kernel.org>,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
Brian Norris <computersforpeace@gmail.com>,
Richard Weinberger <richard@nod.at>,
Boris Brezillon <boris.brezillon@bolin.com>,
Marek Vasut <marek.vasut@gmail.com>
Subject: Re: [PATCH] mtd: nand: Add support for reading ooblayout from device tree
Date: Sat, 12 May 2018 11:38:26 -0300 [thread overview]
Message-ID: <1526135906.4971.0@smtp.crapouillou.net> (raw)
In-Reply-To: <20180512154223.3b81c7f7@bbrezillon>
Le sam. 12 mai 2018 à 10:42, Boris Brezillon
<boris.brezillon@bootlin.com> a écrit :
> On Sat, 12 May 2018 08:55:40 -0300
> Paul Cercueil <paul@crapouillou.net> wrote:
>
>> Hi Boris,
>>
>> Le 12 mai 2018 02:55, Boris Brezillon <boris.brezillon@bootlin.com>
>> a écrit :
>> >
>> > Hi Paul,
>> >
>> > On Fri, 11 May 2018 23:29:12 +0200
>> > Paul Cercueil <paul@crapouillou.net> wrote:
>> >
>> > > By specifying the properties "mtd-oob-ecc" and "mtd-oob-free",
>> it is
>> > > now possible to specify from devicetree where the ECC data is
>> located
>> > > inside the OOB region.
>> >
>> > Why would we want to do that? I mean, ECC/free regions are ECC
>> > controller dependent (and NAND chip dependent for the OOB size
>> part),
>> > so there's no reason to describe it in the DT. And more
>> importantly,
>> > people are likely to get it wrong.
>> >
>> > I'm curious, why do you need that?
>>
>> Good question.
>>
>> The reason is that some SoCs have no ECC controller.
>> The various boards for these SoCs then all use a different layout.
>
> Okay. Still think defining the layouts in the DT is a bad idea. We
> can add a jz4740 specific property to define the layout id
> (ingenic,nand-oob-layout = <layout-id>), but not a generic way to
> define custom layouts for all kind of NAND controller.
Okay.
>>
>> My motivation is to get rid of this (move it to devicetree):
>>
>> https://elixir.bootlin.com/linux/latest/source/arch/mips/jz4740/board-qi_lb60.c#L93
>> And enable the support of other boards with custom OOB layouts.
>
> Can you list the different layouts you have? I'm pretty sure there's a
> pattern. Maybe we can even deduce the layout from the page size or OOB
> size.
This is the other layout I have for another ingenic device:
http://projects.qi-hardware.com/index.php/p/qi-kernel/source/tree/od-2011-09-18/arch/mips/jz4740/board-a320.c#L125
Page size and OOB size are the same between these two devices.
-Paul
next prev parent reply other threads:[~2018-05-12 14:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180512115551.56C6E20787@mail.bootlin.com>
2018-05-12 13:42 ` Boris Brezillon
2018-05-12 14:38 ` Paul Cercueil [this message]
2018-05-12 15:00 ` Boris Brezillon
2018-05-12 17:42 ` Paul Cercueil
2018-05-12 18:02 ` Boris Brezillon
2018-05-12 18:30 ` Paul Cercueil
2018-05-11 21:29 Paul Cercueil
2018-05-12 5:55 ` Boris Brezillon
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