From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sekhar Nori <nsekhar@ti.com>
Subject: Re: [PATCH 07/12] memory: davinci-aemif: introduce AEMIF driver
Date: Wed, 27 Nov 2013 09:35:58 +0530
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To: "ivan.khoronzhuk" <ivan.khoronzhuk@ti.com>, "Shilimkar, Santosh" <santosh.shilimkar@ti.com>, Rob Landley <rob@landley.net>, Russell King <linux@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, "Strashko,
 Grygorii" <grygorii.strashko@ti.com>, Pawel Moll <pawel.moll@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Stephen Warren <swarren@wwwdotorg.org>, Kumar Gala <galak@kernel.crashing.org>, Rob Herring <rob.herring@calxeda.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
List-Id: devicetree@vger.kernel.org

On Tuesday 26 November 2013 11:14 PM, ivan.khoronzhuk wrote:

>>> +static int davinci_aemif_probe(struct platform_device *pdev)
>>> +{
>>> +       int ret  = -ENODEV, i;
>>> +       struct resource *res;
>>> +       struct device *dev = &pdev->dev;
>>> +       struct device_node *np = dev->of_node;
>>> +
>>> +       if (np == NULL)
>>> +               return 0;
>>> +
>>> +       if (aemif) {
>>> +               dev_err(dev, "davinci_aemif driver is in use currently\n");
>>> +               return -EBUSY;
>>> +       }
>>
>> Why expressly prevent multiple AEMIF devices? Its entirely conceivable
>> to have two memories like NAND and NOR flash connect to two different
>> AEMIF interfaces.
>>
> 
> It can be, but I'm not sure if it is needed. Currently I've not seen case where
> more than 2 cses were used, I mean we have 2 cs free, why do we need the second AEMIF
> controller?

One usual reason is pinmux constraints. Its probably not a concern on
the device you are working with right now but as devices get smaller,
functionality on pins is multiplexed to handle multiple different use cases.

Thanks,
Sekhar

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