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Message-ID: <alpine.LFD.2.00.1002222235560.4136@localhost.localdomain>
Date: Mon, 22 Feb 2010 22:53:04 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: Maxim Levitsky <maximlevitsky@...il.com>
cc: David Woodhouse <dwmw2@...radead.org>,
linux-mtd <linux-mtd@...ts.infradead.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Alex Dubov <oakad@...oo.com>, joern <joern@...fs.org>,
stanley.miao@...driver.com, Vitaly Wool <vitalywool@...il.com>
Subject: Re: [PATCH 13/15] MTD: add few workarounds to nand system for
SmartMedia/xD chips.
On Mon, 22 Feb 2010, Maxim Levitsky wrote:
> On Mon, 2010-02-22 at 22:25 +0100, Thomas Gleixner wrote:
> > On Mon, 22 Feb 2010, Maxim Levitsky wrote:
> >
> > > * Add an option NAND_SMARTMEDIA that can be set by nand driver
> > > If set, it will cause separate ID table to be used, which includes
> > > mask rom devices and new xD cards
> >
> > Why that option ? We can just extend the existing ids table and be
> > done. No extra magic needed.
> >
>
> Two reasons.
>
> First of all several xD chips (I belive the Type M) have exactly same
> IDs like normal nand chips. However they don't report capabilities about
> pagesize, blocksize, etc.
You mean that crap ?
+ /* xD only */
+ {"xD 512MiB 3,3V", 0xDC, 512, 512, 0x4000, XD_TYPEM},
+ {"xD 1GiB 3,3V", 0xD3, 512, 1024, 0x4000, XD_TYPEM},
+ {"xD 2GiB 3,3V", 0xD5, 512, 2048, 0x4000, XD_TYPEM},
Oh well, that's a perfect example of designed by comittee shit.
They abuse the 2k chips IDs and define crappy sizes just to fit the
stupid spec.
> I am confident that these cards have an internal FTL and controller, and
> just 'emulate' that nand interface.
Either that or the adapter translates the 512B commands to 2K
commands. I bet on the latter. AFAIK are xD cards just as stupid as
SmartMedia ones, i.e. bare NAND chips in a flat plastic housing with
gold contacts.
> Also, my card reports write protect, although, xD cards don't have any
> 'switch' to make them protected.
Neither have SmartMedia Cards nor bare NAND chips. WP is a pin on the
interface which is controlled by the adapter hardware.
> Even if there were readonly ROM xD cards (the odds of this are virtually
> zero), these won't just expose this in WP bit.
Hmm, I wonder whether that horror has the WP bit inverted.
Thanks,
tglx
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