From mboxrd@z Thu Jan  1 00:00:00 1970
From: Artem Bityutskiy <dedekind1@gmail.com>
Subject: Re: [PATCH v3.4-rc3] MTD: NAND: ams-delta: Fix request_mem_region()
 failure
Date: Wed, 25 Apr 2012 18:13:38 +0300
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To: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Cc: David Woodhouse <dwmw2@infradead.org>, Tony Lindgren <tony@atomide.com>, Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-omap@vger.kernel.org


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On Tue, 2012-04-17 at 15:49 +0200, Janusz Krzysztofik wrote:
> A call to request_mem_region() has been introduced in the omap-gpio
> driver recently (commit 96751fcbe5438e95514b025e9cee7a6d38038f40,
> "gpio/omap: Use devm_ API and add request_mem_region"). This change
> prevented the Amstrad Delta NAND driver, which was doing the same in
> order to take control over OMAP MPU I/O lines that the NAND device hangs
> off, from loading successfully.
>=20
> There is another driver, omap-keypad, which also manipulates OMAP MPUIO
> registers, but has never been calling request_mem_region() on startup,
> so it's not affected by the change in the gpio-omap and works correctly.
>=20
> Drop request_mem_region() call and related bits from ams-delta NAND
> driver.
>=20
> Created and tested against linux-3.4-rc3.
>=20
> Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>

How about race conditions? Where is the guarantee that these 2 drivers
won't affect each other when doing I/O at the same time to the same HW
resources?

--=20
Best Regards,
Artem Bityutskiy

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