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Date: Mon, 21 Jun 2010 11:15:51 +0400
From: Anton Vorontsov <cbouatmailru@gmail.com>
To: Barry Song <21cnbao@gmail.com>
Subject: Re: [Uclinux-dist-devel] [PATCH 1/2] mtd: m25p80:
	Reworkprobing/JEDEC code
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Cc: David Brownell <dbrownell@users.sourceforge.net>,
	Artem Bityutskiy <dedekind1@gmail.com>,
	linux-kernel@vger.kernel.org, "Song,
	Barry" <Barry.Song@analog.com>, linuxppc-dev@ozlabs.org,
	linux-mtd@lists.infradead.org, uclinux-dist-devel@blackfin.uclinux.org,
	Andrew Morton <akpm@linux-foundation.org>
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On Mon, Jun 21, 2010 at 11:27:31AM +0800, Barry Song wrote:
[...]
> > How about we add a non_jedec flag in platform_data, if the flag is 1, we
> > let the detection pass even though the ID is 0? Otherwise, we need a
> > valid ID?
> Here i mean:

This will break at least OF-enabled platforms (e.g. PowerPC),
they assume that the driver will success for non-JEDEC flashes.
OF platforms don't pass platform data, and even if they did,
device tree doesn't specify if the flash is JEDEC or non-JEDEC.

Which is why I think that, by default, the driver should
successfully register the flash even if JEDEC probe fails. So,
instead of checking for "!non_jedec", I would recommend
"force_jedec" check.

> Index: drivers/mtd/devices/m25p80.c
> ===================================================================
> --- drivers/mtd/devices/m25p80.c	(revision 8927)
> +++ drivers/mtd/devices/m25p80.c	(revision 8929)
> @@ -795,8 +795,13 @@
> 
>  		jid = jedec_probe(spi);
>  		if (!jid) {
> -			dev_info(&spi->dev, "non-JEDEC variant of %s\n",
> -				 id->name);
> +			if (!data->non_jedec) {
> +				dev_err(&spi->dev, "fail to detect%s\n",
> +						id->name);
> +				return -ENODEV;
> +			} else
> +				dev_info(&spi->dev, "non-JEDEC variant of %s\n",
> +						id->name);
>  		} else if (jid != id) {

-- 
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2