linux-kernel - Re: [PATCH v3 3/3] mtd/nand : workaround for Freescale FCM to support large-page Nand chip

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Date:	Mon, 28 Nov 2011 15:41:16 -0600
From:	Scott Wood <scottwood@...escale.com>
To:	LiuShuo <b35362@...escale.com>
CC:	<dwmw2@...radead.org>, <Artem.Bityutskiy@...ia.com>,
	<linux-mtd@...ts.infradead.org>, <linuxppc-dev@...ts.ozlabs.org>,
	<akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
	<leoli@...escale.com>, Liu Shuo <Shuo.Liu@...escale.com>,
	Shengzhou Liu <Shengzhou.Liu@...escale.com>
Subject: Re: [PATCH v3 3/3] mtd/nand : workaround for Freescale FCM to support
 large-page Nand chip

On 11/23/2011 06:14 AM, LiuShuo wrote:
> 于 2011年11月23日 07:55, Scott Wood 写道:
>> On 11/15/2011 03:29 AM, b35362@...escale.com wrote:
>>> From: Liu Shuo<b35362@...escale.com>
>>>
>>> -        if (elbc_fcm_ctrl->oob || elbc_fcm_ctrl->column != 0 ||
>>> +        if (elbc_fcm_ctrl->column>= mtd->writesize) {
>>> +            /* write oob */
>>> +            if (priv->page_size>  1) {
>>> +                /* when pagesize of chip is greater than 2048,
>>> +                 * we have to write full page to write spare
>>> +                 * region, so we fill '0xff' to main region
>>> +                 * and some bytes of spare region which we
>>> +                 * don't want to rewrite.
>>> +                 * (write '1' won't change the original value)
>>> +                 */
>>> +                memset(elbc_fcm_ctrl->buffer, 0xff,
>>> +                        elbc_fcm_ctrl->column);
>> I don't like relying on this -- can we use RNDIN instead to do a
>> discontiguous write?
>>
> I have no better way to implement it now.
> Some chips have 'NOP' limitation, so I don't use the FIR_OP_UA to do a
> oob write.

I don't think each RNDIN counts separately against NOP (someone correct
me if I'm wrong).  You're writing discontiguous regions of the page in
one operation.

-Scott

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