linux-kernel - Re: [PATCH for-4.4 1/2] mtd: spi-nor: fix Spansion regressions (aliased with Winbond)

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Message-ID: <56F86443.4050901@universe-factory.net>
Date:	Mon, 28 Mar 2016 00:52:51 +0200
From:	Matthias Schiffer <mschiffer@...verse-factory.net>
To:	Brian Norris <computersforpeace@...il.com>,
	linux-mtd@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, Daniel Kurtz <djkurtz@...omium.org>,
	Marek Vasut <marex@...x.de>,
	Bayi Cheng <bayi.cheng@...iatek.com>,
	Rafał Miłecki <zajec5@...il.com>,
	Felix Fietkau <nbd@...nwrt.org>,
	Eddie Huang (黃智傑) 
	<eddie.huang@...iatek.com>,
	Milton Chiang (江明晏) 
	<Milton.Chiang@...iatek.com>
Subject: Re: [PATCH for-4.4 1/2] mtd: spi-nor: fix Spansion regressions
 (aliased with Winbond)

On 03/26/2016 07:57 PM, Matthias Schiffer wrote:
> On 12/15/2015 07:48 PM, Brian Norris wrote:
>> Spansion and Winbond have occasionally used the same manufacturer ID,
>> and they don't support the same features. Particularly, writing SR=0
>> seems to break read access for Spansion's s25fl064k. Unfortunately, we
>> don't currently have a way to differentiate these Spansion and Winbond
>> parts, so rather than regressing support for these Spansion flash, let's
>> drop the new Winbond lock/unlock support for now. We can try to address
>> Winbond support during the next release cycle.
>>
>> Original discussion:
>>
>> http://patchwork.ozlabs.org/patch/549173/
>> http://patchwork.ozlabs.org/patch/553683/
>>
> 
> I have a few devices with a s25fl064k lying around, and I was not able to
> reproduce this issue. I've re-applied "mtd: spi-nor: disable protection for
> Winbond flash at startup" and the flash is readable just fine.
> 
> On the contrary, I've come across a board with a s25fl064k that comes up
> locked, so removing the protection bits would be necessary. (I was not yet
> able to check if the patch actually fixes writing to the flash on this
> board, as I don't have access to the device myself, but I hope to get a
> response on that soon.)
> 
> Regards,
> Matthias
> 

I made the mistake of trusting the kernel log and OpenWrt Wiki when making
my previous tests.

All of the boards I was talking about in my last mail actually have a
Winbond w25q64, not a s25fl064k (two board I tested the patch on, and the
board that was reported to come up locked). The kernel detects the w25q64
as s25fl064k, as these two flash chips have the same JEDEC ID 0xef4017.

Matthias



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