From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Paul Cercueil <paul@crapouillou.net>
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 17:00:34 +0200 [thread overview]
Message-ID: <20180512170034.12779313@bbrezillon> (raw)
In-Reply-To: <1526135906.4971.0@smtp.crapouillou.net>
On Sat, 12 May 2018 11:38:26 -0300
Paul Cercueil <paul@crapouillou.net> wrote:
> 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.
Indeed. Do you know if there are other kind of layouts in the wild?
Note that <layout-id> can be a string, so if each each board is
defining its own layout, you could specify the board name here.
Otherwise, if you just have those 2 patterns, you can just name them
"contiguous" and "interleaved".
next prev parent reply other threads:[~2018-05-12 15:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180512115551.56C6E20787@mail.bootlin.com>
2018-05-12 13:42 ` [PATCH] mtd: nand: Add support for reading ooblayout from device tree Boris Brezillon
2018-05-12 14:38 ` Paul Cercueil
2018-05-12 15:00 ` Boris Brezillon [this message]
2018-05-12 17:42 ` Paul Cercueil
2018-05-12 18:02 ` Boris Brezillon
2018-05-12 18:30 ` Paul Cercueil
2018-05-12 11:55 Paul Cercueil
-- strict thread matches above, loose matches on Subject: below --
2018-05-11 21:29 Paul Cercueil
2018-05-12 5:55 ` Boris Brezillon
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