Re: [PATCH v1 4/5] mtd: rawnand: meson: clear OOB buffer before read

From: Arseniy Krasnov <avkrasnov@sberdevices.ru>
To: Richard Weinberger <richard.weinberger@gmail.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Liang Yang <liang.yang@amlogic.com>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Jianxin Pan <jianxin.pan@amlogic.com>,
	Yixun Lan <yixun.lan@amlogic.com>, <oxffffaa@gmail.com>,
	<kernel@sberdevices.ru>, <linux-mtd@lists.infradead.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-amlogic@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	yonghui.yu <yonghui.yu@amlogic.com>
Subject: Re: [PATCH v1 4/5] mtd: rawnand: meson: clear OOB buffer before read
Date: Thu, 4 May 2023 14:40:30 +0300	[thread overview]
Message-ID: <213a4f8d-b660-8644-87ad-3791d95cafc2@sberdevices.ru> (raw)
In-Reply-To: <CAFLxGvwfi2RH3y2M6n0vqUHarp6DwR-wT7oBto3raA7oC3nJvg@mail.gmail.com>

On 03.05.2023 22:48, Richard Weinberger wrote:
> Sorry for joining the party late.
> 
> On Wed, May 3, 2023 at 10:07 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>>> So for me main question here is:
>>>
>>> How JFFS2 should work with controllers where we can't update data and OOB
>>> independently? Driver of this filesystem knows nothing about this features of
>>> the controller.
>>>
>>> Or JFFS2 works incorrectly in my case when it tries to call write page callback
>>> after calling write OOB callback (IIUC it is better to ask Richard as You mentioned above).
>>>
>>> Or may be it is better to suppress OOB write callback (or set it to NULL) in this
>>> driver as in vendor's driver?
>>
>> I would assume using the unprotected free OOB bytes to store the
>> cleanmarkers should work. But that's a bit fragile and very filesystem
>> oriented. I don't like this much. But on the other side JFFS2 is
>> legacy, you should use UBI (which does not play with OOB areas) :-)
> 
> Please note that JFFS2's main use case is NOR flash. Support for NAND
> flash was never
> considered as fully complete/stable. That's why UBIFS (JFFS3 in the
> very beginning)
> was invented.

Hello Richard!

Thanks for this details! But I think it will be useful to make JFFS2 work correctly
on this chip :) Anyway i think it is not rare/exotic case to use JFFS2 on NAND.

Thanks, Arseniy

> 
> Thanks,
> //richard

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