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From:   Chuanhong Guo <gch981213@gmail.com>
Date:   Mon, 16 May 2022 22:10:08 +0800
Message-ID: <CAJsYDVJ=WRT270mj2jNc+yy0v_XRpyH8N+GOmkNJv1zAh76rDA@mail.gmail.com>
Subject: Re: [PATCH 1/2] mtd: spinand: add support for detection with param page
To:     Frieder Schrempf <frieder.schrempf@kontron.de>
Cc:     linux-mtd@lists.infradead.org,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Patrice Chotard <patrice.chotard@foss.st.com>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        Christophe Kerello <christophe.kerello@foss.st.com>,
        Mark Brown <broonie@kernel.org>,
        Daniel Palmer <daniel@0x0f.com>,
        open list <linux-kernel@vger.kernel.org>
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Hi!

On Mon, May 16, 2022 at 3:38 PM Frieder Schrempf
<frieder.schrempf@kontron.de> wrote:
>
> Hi Chuanhong,
>
> Am 14.04.22 um 16:34 schrieb Chuanhong Guo:
> > SPI-NAND detection using chip ID isn't always reliable.
> > Here are two known cases:
> > 1. ESMT uses JEDEC ID from other vendors. This may collapse with future
> >    chips.
> > 2. Winbond W25N01KV uses the exact same JEDEC ID as W25N01GV while
> >    having completely different chip parameters.
>
> I think they share the same first byte of the JEDEC ID, but the second
> byte actually differs and would allow to differentiate between them, right?

No. For the 128M version, all 3 bytes are the same between
W25N01GV and W25N01KV.

>
> I have this patchset [1] that I didn't manage to send upstream yet which
> adds support for the W25N02KV. I added the second ID byte to detect them.
>
> Still your approach using the ONFI data is more flexible of course and
> probably a better way to handle this. I will see if I can find some time
> to add support for the W25N02KV based on your patches.

Don't do that. I abandoned this patchset because I later found that
some early W25N01GV doesn't contain a parameter page at all,
which means detecting W25N01GV/KV using only the parameter
page is unreliable.
I think what Boris proposed earlier in v1 (use parameter page
just to distinguish the two chips) is the correct way to go.

BTW I was making this patchset for a potential future ID conflict
between ESMT and GigaDevice, and I don't actually need to
deal with the W25N01GV/KV nonsense now, so I don't have a
plan for send a new version of this atm.

-- 
Regards,
Chuanhong Guo