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Subject: Re: [PATCH v3 18/27] mtd: nand: omap2: Implement NAND ready using
 gpiolib
To: Boris Brezillon <boris.brezillon@free-electrons.com>
References: <1442588029-13769-1-git-send-email-rogerq@ti.com>
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 <20151027091235.03dba8c5@bbrezillon>
CC: Brian Norris <computersforpeace@gmail.com>, <tony@atomide.com>,
        <dwmw2@infradead.org>, <ezequiel@vanguardiasur.com.ar>,
        <javier@dowhile0.org>, <fcooper@ti.com>, <nsekhar@ti.com>,
        <linux-mtd@lists.infradead.org>, <linux-omap@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Alex Smith <alex.smith@imgtec.com>,
        Harvey Hunt <harvey.hunt@imgtec.com>
From: Roger Quadros <rogerq@ti.com>
Message-ID: <562F393C.1030701@ti.com>
Date: Tue, 27 Oct 2015 10:43:40 +0200
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Boris,

On 27/10/15 10:12, Boris Brezillon wrote:
> Hi Roger,
> 
> On Tue, 27 Oct 2015 10:03:02 +0200
> Roger Quadros <rogerq@ti.com> wrote:
> 
>> On 26/10/15 22:49, Brian Norris wrote:
>>>
>>> Others have been looking at using GPIOs for the ready/busy pin too. At a
>>> minimum, we need an updated DT binding doc for this, since I see you're
>>> adding this via device tree in a later patch (I don't see any DT binding
>>> patch for this; but I could just be overlooking it). It'd also be great
>>> if this support was moved to nand_dt_init() so other platforms can
>>> benefit, but I won't require that.
>>>
>>> Also, previous [0] proposers had suggested 'rb-gpios', not 'ready-gpio'
>>> (the hardware docs typically call it 'rb' for ready/busy, FWIW). I don't
>>> really care, but the name should be going into a doc, so we can choose
>>> the same one everywhere.
>>>
>>> EDIT: looks like the discussion was partly here [1] and it seems we're
>>> landing on "rb-gpios" in the latest version [2]. Can we stick with that?
>>
>> Why should it be "rb-gpios" and not "rb-gpio"?
>> I don't think there are multiple gpios for r/b# function.
> 
> Because it's supposed to be a generic binding, and some NAND chips
> embed several dies, thus exposing several CS and RB pins, hence the
> rb-gpios name.
> Also, as described here [1], the convention is to name your property
> <name>-gpios even if you only need one gpio.

Makes sense now. Thanks for the explanation.
I'll update this patch to use rb-gpios and update the binding doc as well.

--
cheers,
-roger