From: Artem Bityutskiy <dedekind1@gmail.com>
To: b35362@freescale.com
Cc: scottwood <scottwood@freescale.com>,
linuxppc-dev@ozlabs.org, Li Yang <leoli@freescale.com>,
dwmw2@infradead.org, linux-mtd@lists.infradead.org
Subject: Re: [PATCH v2] mtd/nand : workaround for Freescale FCM to support large-page Nand chip
Date: Mon, 15 Aug 2011 18:59:09 +0300 [thread overview]
Message-ID: <1313423954.8691.17.camel@sauron> (raw)
In-Reply-To: <1310446122-18050-1-git-send-email-b35362@freescale.com>
On Tue, 2011-07-12 at 12:48 +0800, b35362@freescale.com wrote:
> + /*
> + * Hack for supporting the flash chip whose writesize is
> + * larger than 2K bytes.
> + */
> + if (mtd->writesize > 2048) {
> + elbc_fcm_ctrl->subpage_shift = ffs(mtd->writesize >> 11) - 1;
> + elbc_fcm_ctrl->subpage_mask =
> + (1 << elbc_fcm_ctrl->subpage_shift) - 1;
> + /*
> + * Rewrite mtd->writesize, mtd->oobsize, chip->page_shift
> + * and chip->pagemask.
> + */
> + mtd->writesize = 2048;
> + mtd->oobsize = 64;
> + chip->page_shift = ffs(mtd->writesize) - 1;
> + chip->pagemask = (chip->chipsize >> chip->page_shift) - 1;
> + }
So basically if the flash has 4KiB NAND pages, you are considering it as
a flash with 2KiB NAND pages. But surely this will work only if the
underlying flash has NOP 2 at least. Or even, if you consider that JFFS2
and YAFFS want to write to OOB, you need NOP 4 (2 ECC writes and 2
writes from YAFFS/JFFS2) ? So this won't work for NOP1 flashes? Isn't it
an ugly hack?
--
Best Regards,
Artem Bityutskiy
WARNING: multiple messages have this Message-ID (diff)
From: Artem Bityutskiy <dedekind1@gmail.com>
To: b35362@freescale.com
Cc: scottwood <scottwood@freescale.com>,
linuxppc-dev@ozlabs.org, dwmw2@infradead.org,
linux-mtd@lists.infradead.org
Subject: Re: [PATCH v2] mtd/nand : workaround for Freescale FCM to support large-page Nand chip
Date: Mon, 15 Aug 2011 18:59:09 +0300 [thread overview]
Message-ID: <1313423954.8691.17.camel@sauron> (raw)
In-Reply-To: <1310446122-18050-1-git-send-email-b35362@freescale.com>
On Tue, 2011-07-12 at 12:48 +0800, b35362@freescale.com wrote:
> + /*
> + * Hack for supporting the flash chip whose writesize is
> + * larger than 2K bytes.
> + */
> + if (mtd->writesize > 2048) {
> + elbc_fcm_ctrl->subpage_shift = ffs(mtd->writesize >> 11) - 1;
> + elbc_fcm_ctrl->subpage_mask =
> + (1 << elbc_fcm_ctrl->subpage_shift) - 1;
> + /*
> + * Rewrite mtd->writesize, mtd->oobsize, chip->page_shift
> + * and chip->pagemask.
> + */
> + mtd->writesize = 2048;
> + mtd->oobsize = 64;
> + chip->page_shift = ffs(mtd->writesize) - 1;
> + chip->pagemask = (chip->chipsize >> chip->page_shift) - 1;
> + }
So basically if the flash has 4KiB NAND pages, you are considering it as
a flash with 2KiB NAND pages. But surely this will work only if the
underlying flash has NOP 2 at least. Or even, if you consider that JFFS2
and YAFFS want to write to OOB, you need NOP 4 (2 ECC writes and 2
writes from YAFFS/JFFS2) ? So this won't work for NOP1 flashes? Isn't it
an ugly hack?
--
Best Regards,
Artem Bityutskiy
next prev parent reply other threads:[~2011-08-15 15:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-12 4:48 [PATCH v2] mtd/nand : workaround for Freescale FCM to support large-page Nand chip b35362
2011-07-12 4:48 ` b35362
2011-08-03 6:15 ` Li Yang-R58472
2011-08-03 6:15 ` Li Yang-R58472
2011-08-15 15:59 ` Artem Bityutskiy [this message]
2011-08-15 15:59 ` Artem Bityutskiy
2011-08-15 16:11 ` Scott Wood
2011-08-15 16:11 ` Scott Wood
2011-08-15 16:24 ` Artem Bityutskiy
2011-08-15 16:24 ` Artem Bityutskiy
2011-09-02 7:10 ` Stijn Devriendt
2011-09-02 7:10 ` Stijn Devriendt
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