From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Sascha Hauer <sha@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] mtd: nand: fix nand_lock/unlock() function
Date: Thu, 15 Nov 2018 09:32:28 +0100 [thread overview]
Message-ID: <6b21d190-ee47-5ffc-bfe8-59604ac217a3@pengutronix.de> (raw)
In-Reply-To: <20181115080214.4iyo6jojt6oclxhb@pengutronix.de>
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On 11/15/18 9:02 AM, Sascha Hauer wrote:
> On Wed, Nov 14, 2018 at 12:04:27PM +0100, Marc Kleine-Budde wrote:
>> From: White Ding <bpqw@micron.com>
>>
>> Do nand reset before write protect check.
>>
>> If we want to check the WP# low or high through STATUS READ and check bit 7,
>> we must reset the device, other operation (eg.erase/program a locked block) can
>> also clear the bit 7 of status register.
>>
>> As we know the status register can be refreshed, if we do some operation to trigger it,
>> for example if we do erase/program operation to one block that is locked, then READ STATUS,
>> the bit 7 of READ STATUS will be 0 indicate the device in write protect, then if we do
>> erase/program operation to another block that is unlocked, the bit 7 of READ STATUS will
>> be 1 indicate the device is not write protect.
>> Suppose we checked the bit 7 of READ STATUS is 0 then judge the WP# is low (write protect),
>> but in this case the WP# maybe high if we do erase/program operation to a locked block,
>> so we must reset the device if we want to check the WP# low or high through STATUS READ and
>> check bit 7.
>
> Have you observed a failure this patch fixes or what is your motivation
> to send this patch?
A $CUSTOMER send me in private a fix needed for the micron NAND chip
found his Phytec board or a board they derived from it. I noticed that
the fix is in mainline Linux, too and I decided to cherry pick it into
barebox.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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next prev parent reply other threads:[~2018-11-15 8:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 11:04 Marc Kleine-Budde
2018-11-15 8:02 ` Sascha Hauer
2018-11-15 8:32 ` Marc Kleine-Budde [this message]
2018-11-16 7:33 ` Sascha Hauer
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