From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <532B4173.9010208@ti.com>
Date: Thu, 20 Mar 2014 15:28:51 -0400
From: Santosh Shilimkar <santosh.shilimkar@ti.com>
MIME-Version: 1.0
To: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>, Brian Norris
 <computersforpeace@gmail.com>
Subject: Re: [PATCH 2/3] mtd: davinci-nand: add dts property for
 NAND_NO_SUBPAGE_WRITE option
References: <1395335184-4745-1-git-send-email-ivan.khoronzhuk@ti.com>
 <1395335184-4745-3-git-send-email-ivan.khoronzhuk@ti.com>
 <532B2183.2080309@ti.com> <20140320172912.GW31517@norris-Latitude-E6410>
 <532B2766.6090506@ti.com> <D69011BE-C37F-4085-B992-45F6F32AF1D0@gmail.com>
 <532B2D3F.6050004@ti.com> <20140320185452.GB21018@ld-irv-0074>
 <532B3D74.6070703@ti.com> <532B40E5.4070201@ti.com>
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Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, grygorii.strashko@ti.com,
 Russell King - ARM Linux <linux@arm.linux.org.uk>, pawel.moll@arm.com,
 ijc+devicetree@hellion.org.uk, linux-doc@vger.kernel.org,
 linux-kernel@vger.kernel.org, Murali Karicheri <m-karicheri2@ti.com>,
 robh+dt@kernel.org, linux-mtd@lists.infradead.org,
 linux-arm-kernel@lists.infradead.org, rob@landley.net, galak@codeaurora.org,
 David Woodhouse <dwmw2@infradead.org>, Warner Losh <imp@bsdimp.com>
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On Thursday 20 March 2014 03:26 PM, Ivan Khoronzhuk wrote:
> 
> On 03/20/2014 09:11 PM, Santosh Shilimkar wrote:
>> On Thursday 20 March 2014 02:54 PM, Brian Norris wrote:
>>> On Thu, Mar 20, 2014 at 02:02:39PM -0400, Santosh Shilimkar wrote:
>>>> On Thursday 20 March 2014 01:44 PM, Warner Losh wrote:
>>>>> I though sub page writing was one of the fields in the onfi and/or jedec(toggle) meta data structures. Have you looked there?
>>>>>
>>>> Am not sure if I follow you. The limitation is from the TI NAND controller(AEMIF) and
>>>> not the NAND memory.
>>> That doesn't match the patch description, which says "that flash doesn't
>>> support subpage writing". Flash != flash controller.
>>>
>> Patch description is indeed doesn't reflect the actual issue.
>>
>>> Which one is it? If it's a controller limitation, I think we should be
>>> able to pull this from a "compatible" property, no?
>>>
>> Just to be accurate, the limitation(bug) is on the controller found on Keystone
>> SOCs. AEMIF controller is also used on DaVinci SOCs which don't seems to have
>> any issue. So even for compatible, you need to add keystone specific one.
>> Hence thought dt property is better option.
>>

> 
> I will use compatible approach.
> We have keystone compatible in k2hk-evm.dts,
> so I need to add it only in the davinci-nand driver.
> I will add the following:
> 
> if (of_device_is_compatible(np, "ti,keystone-nand")) {
>             pdata->options |= NAND_NO_SUBPAGE_WRITE;
>  }
> 
> ...
> 
> static const struct of_device_id davinci_nand_of_match[] = {
>     {.compatible = "ti,davinci-nand", },
>     {.compatible = "ti,keystone-nand", },
>     {},
> };
> 
Looks good. I think you should go ahead and respin the patch
with above.

Regards,
Santosh