From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Alexander Dahl <ada@thorsis.com>,
Tudor Ambarus <tudor.ambarus@microchip.com>,
linux-mtd@lists.infradead.org,
Boris Brezillon <bbrezillon@kernel.org>
Subject: Re: atmel nand bindings vs. actual dts files
Date: Tue, 4 Jun 2019 03:53:01 +0200 [thread overview]
Message-ID: <20190604015301.GK3558@piout.net> (raw)
In-Reply-To: <20190430113242.5cad2f16@xps13>
On 30/04/2019 11:32:42+0200, Miquel Raynal wrote:
> Hi Alexander,
>
> Alexander Dahl <ada@thorsis.com> wrote on Tue, 30 Apr 2019 11:24:44
> +0200:
>
> > Hello Miquèl,
> >
> > Am Montag, 29. April 2019, 11:55:40 CEST schrieb Miquel Raynal:
> > > Alexander Dahl <ada@thorsis.com> wrote on Thu, 07 Mar 2019 17:25:17
> > > > Am Mittwoch, 6. März 2019, 15:07:52 CET schrieb Alexander Dahl:
> > > > > So instead of "always 0x800000" that node has 0x2 as third entry for the
> > > > > 'reg' property. Why is that?
> > > >
> > > > I didn't investigate that further yet, but I'm curious, so if anyone
> > > > knows?
> > >
> > > I suppose the bindings [1] explain the situation.
> > >
> > > [1]
> > > https://elixir.bootlin.com/linux/v5.0/source/Documentation/devicetree/bindi
> > > ngs/mtd/atmel-nand.txt#L32
> >
> > No, that was not what I wanted to know. The bindings says for that reg
> > property: “3rd entry: the memory region size (always 0x800000)”
> >
> > This is true for some dts files including this nand node, but not for all,
> > some have this:
> >
> > nand@3 {
> > reg = <0x3 0x0 0x800000>;
> >
> > Others have this:
> >
> > nand@3 {
> > reg = <0x3 0x0 0x2>;
> >
> > The second contradicts the binding doc. Most of this was changed when
> > switching from the old bindings in changeset v4.12-rc1-7-g1004a2977bdc by
> > Boris Brezillon. I wanted to know why the difference?
>
> Indeed. Adding Alexandre who might also have an idea and Tudor for
> reference.
>
I'd say that <0x3 0x0 0x2> only works because ioremap will always map a
4k page and DMA is used so we are not accessing anything beyond that
page using the virtual address.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2019-06-04 1:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-06 14:07 atmel nand bindings vs. actual dts files Alexander Dahl
2019-03-07 16:25 ` Alexander Dahl
2019-04-29 9:55 ` Miquel Raynal
2019-04-30 9:24 ` Alexander Dahl
2019-04-30 9:32 ` Miquel Raynal
2019-06-04 1:53 ` Alexandre Belloni [this message]
2019-06-04 7:43 ` Boris Brezillon
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