linux-kernel - Re: [PATCH] mtd: increase max page/OOB size to support 16K pagesize NAND

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Date:	Fri, 13 Dec 2013 00:01:18 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Caizhiyong <caizhiyong@...ilicon.com>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	David Woodhouse <David.Woodhouse@...el.com>,
	Quyaxin <quyaxin@...ilicon.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Huang Shijie <b32955@...escale.com>,
	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
	"Wanglin (Albert)" <albert.wanglin@...ilicon.com>
Subject: Re: [PATCH] mtd: increase max page/OOB size to support 16K pagesize
 NAND

On Fri, Dec 13, 2013 at 05:03:49AM +0000, Caizhiyong wrote:
> From: Cai Zhiyong <caizhiyong@...wei.com>
> Date: Fri, 13 Dec 2013 12:52:46 +0800
> Subject: [PATCH] mtd: increase max page/OOB size to support 16K pagesize NAND.
> 
> The Toshiba's TC58TEG5DCJTA pagesize is 16K, oob size is 1280 bytes.
> So increase the NAND_MAX_OOBSIZE and NAND_MAX_PAGESIZE.

It would help if we had nand_base/nand_ids support for TC58TEG5DCJTA
before we try to increase NAND_MAX_PAGESIZE and NAND_MAX_OOBSIZE yet
again. AFAICT, nand_base will not detect new, large Toshiba flash
properly anyway.

> Signed-off-by: Cai Zhiyong <caizhiyong@...wei.com>
> ---
>  include/linux/mtd/nand.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
> index f3ea8da..2f0a7f2 100644
> --- a/include/linux/mtd/nand.h
> +++ b/include/linux/mtd/nand.h
> @@ -56,8 +56,8 @@ extern int nand_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
>   * is supported now. If you add a chip with bigger oobsize/page
>   * adjust this accordingly.
>   */
> -#define NAND_MAX_OOBSIZE	744
> -#define NAND_MAX_PAGESIZE	8192
> +#define NAND_MAX_OOBSIZE	1280
> +#define NAND_MAX_PAGESIZE	16384

It might be time to draw a line in the sand: next person who needs to
increase MAX_{PAGE,OOB}SIZE gets the job of killing the macro? We are
long overdue for dynamic buffer allocation.

There are two drivers that use the macros, plus nand_chip.buffers.*. The
drivers can be weaned off by allocating a small, fixed-size temporary
buffer for the few tasks that need it. With nand_base.c, I think we can
get by with waiting to allocate nand_chip.buffers until after we detect
the writesize/oobsize.

So Cai, are you up for this?

>  
>  /*
>   * Constants for hardware specific CLE/ALE/NCE function
> 

Brian
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