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Date: Tue, 30 Jul 2013 09:34:41 -0700
From: Olof Johansson <olof@lixom.net>
To: Alexander Shiyan <shc_work@mail.ru>
Subject: Re: [PATCH v2 1/4] mtd: nand: gpio: Determine bus width automatically
Message-ID: <20130730163441.GB13634@quad.lixom.net>
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Cc: Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org,
 Ian Campbell <ian.campbell@citrix.com>, Pawel Moll <pawel.moll@arm.com>,
 Stephen Warren <swarren@wwwdotorg.org>,
 Artem Bityutskiy <artem.bityutskiy@linux.intel.com>,
 Rob Herring <rob.herring@calxeda.com>, linux-mtd@lists.infradead.org,
 Brian Norris <computersforpeace@gmail.com>,
 David Woodhouse <dwmw2@infradead.org>
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On Tue, Jul 30, 2013 at 03:05:24PM +0400, Alexander Shiyan wrote:
> This patch provide automatically determine of NAND bus width if
> "bank-width" parameter is ommited.
> Patch depends on "mtd: nand: fix NAND_BUSWIDTH_AUTO for x16 devices".
> 
> Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
> ---
>  .../devicetree/bindings/mtd/gpio-control-nand.txt         |  4 ++--
>  drivers/mtd/nand/gpio.c                                   | 15 ++++++++++-----
>  2 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/gpio-control-nand.txt b/Documentation/devicetree/bindings/mtd/gpio-control-nand.txt
> index 36ef07d..2ac14d8 100644
> --- a/Documentation/devicetree/bindings/mtd/gpio-control-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpio-control-nand.txt
> @@ -15,8 +15,8 @@ Required properties:
>    optional gpio and may be set to 0 if not present.
>  
>  Optional properties:
> -- bank-width : Width (in bytes) of the device.  If not present, the width
> -  defaults to 1 byte.
> +- bank-width : Width (in bytes) of the device. If not present, the bus width
> +  of the device is determined automatically.
>  - chip-delay : chip dependent delay for transferring data from array to
>    read registers (tR).  If not present then a default of 20us is used.
>  - gpio-control-nand,io-sync-reg : A 64-bit physical address for a read

This would break backwards compatibility, something we're now starting to push
back at.

Instead what you can do is add a bank-width-auto property that, if present and
bank-width being absent, will result in the automatic determination of bank
width.


-Olof