linux-kernel - Re: [linux-sunxi] Re: [RFC PATCH 0/9] mtd: nand: add sunxi NAND Flash Controller support

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Date:	Tue, 21 Jan 2014 19:13:31 +0100
From:	Henrik Nordström <henrik@...riknordstrom.net>
To:	linux-sunxi@...glegroups.com
Cc:	dev@...ux-sunxi.org,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-mtd@...ts.infradead.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [linux-sunxi] Re: [RFC PATCH 0/9] mtd: nand: add sunxi NAND
 Flash Controller support

lör 2014-01-18 klockan 05:46 -0800 skrev Boris BREZILLON:

> Do you know which mode are used (X ECC strength / 512 or 1024 bytes ?)
> and
> when they are are selected  (does it depend on the connected NAND
> chip ?) ?

It seems to blindly try some modes until something usable is found.
Varying both chip address size and ECC layout.

Sorry I do not have the exact details on the ECC modes used. Only
analyzed nand controller command traces of A13 BROM trying to load
boot0. The trace can be found at
https://github.com/hno/Allwinner-Info/blob/master/NAND/boot0/A13-brom

>  
>         
>         > - boot0 code is stored only on the first ECC block of each
>         page (1024 
>         > bytes + ecc bytes) 
>         
>         No, it reads a whole page at a time in sequental mode 
>         (data,ecc,data,ecc,data,ecc,data,ecc...).
> 
> 
> Are you sure ?
> This thread says that only the first 1024 bytes of data (+ 96 bytes of
> ECC) of each page are used:

yes I am sure. There was no page access commands between the sectors,
only linear read of data,ecc,data,ecc.

> I'm not a big fan of this approach, because the real media is an MTD
> (NAND) device,
> not a block device.

Hit implementation acks this by not providing a block device.


>         iirc there is an interface for dynamically selecting ECC mode
>         and other 
>         parameers. Or maybe that's only u-boot mtd?
> 
> 
> Haven't found anything authorizing per partiton ECC config, though
> this could be an
> enhancement of the MTD framework.

u-boot have user selectable ecc scheme for some boards. I.e. omap3 based
ones.

other boards select based on NAND size etc.
 
Regards
Henrik


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