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From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Date: Wed, 11 Jul 2018 22:54:43 +0530
Message-ID: <CANc+2y4RpTTJxh+jWjkWgFpuuJRZbtjKgLxXbRAg_M6L1yQ4Jg@mail.gmail.com> (sfid-20180711_192446_393482_DE837316)
Subject: Re: [PATCH v2 23/24] mtd: rawnand: jz4780: Drop the dependency on MACH_JZ4780
To: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: Ralf Baechle <ralf@linux-mips.org>,
        Linux-MIPS <linux-mips@linux-mips.org>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>,
        Richard Weinberger <richard@nod.at>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        linux-mtd@lists.infradead.org,
        David Woodhouse <dwmw2@infradead.org>,
        Brian Norris <computersforpeace@gmail.com>,
        Marek Vasut <marek.vasut@gmail.com>,
        linux-wireless@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
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Sender: linux-wireless-owner@vger.kernel.org

On 10 July 2018 at 22:40, Boris Brezillon <boris.brezillon@bootlin.com> wrote:
> Hi PrasannaKumar,
>
> On Tue, 10 Jul 2018 22:16:50 +0530
> PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> wrote:
>
>> Hi Boris,
>>
>> On 10 July 2018 at 01:39, Boris Brezillon <boris.brezillon@bootlin.com>
>> wrote:
>>
>> > This MACH_JZ4780 dependency is taken care of by JZ4780_NEMC, no need
>> > to repeat it here.
>> >
>> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
>> > ---
>> >  drivers/mtd/nand/raw/Kconfig | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
>> > index 7b5e97719c25..d9cd9608bc2d 100644
>> > --- a/drivers/mtd/nand/raw/Kconfig
>> > +++ b/drivers/mtd/nand/raw/Kconfig
>> > @@ -499,7 +499,7 @@ config MTD_NAND_JZ4740
>> >
>> >  config MTD_NAND_JZ4780
>> >         tristate "Support for NAND on JZ4780 SoC"
>> > -       depends on MACH_JZ4780 && JZ4780_NEMC
>> > +       depends on JZ4780_NEMC
>> >         help
>> >           Enables support for NAND Flash connected to the NEMC on JZ4780
>> > SoC
>> >           based boards, using the BCH controller for hardware error
>> > correction.
>> > --
>> > 2.14.1
>> >
>> >
>> >
>> JZ4780 has MLC NAND.
>
> Hm, the NAND controller supports both MLC and SLC NANDs. Maybe there
> are only boards with MLC NANDs, but that doesn't mean we should remove
> the driver for the controller.

Creator CI20 board which uses JZ4780 SoC is supported by upstream as
of now. It has MLC NAND.

But I agree that removing the driver is too extreme.

>> As MLC NAND is not supported in mainline do you think
>> this patch is required? Even wondering if the driver is required at all.
>
> The fact that MLC NANDs are not supported by UBI is not necessarily
> definitive. I have a branch with all the work we've done to add MLC
> support to UBI [1]. If you have time to invest in it, feel free to take
> over this work.

I am afraid I don't have time as well as knowledge to work on it yet.

> Anyway, the decision to remove this driver is not mine, and this patch
> allows me to at least compile-test this driver.
>
> Regards,
>
> Boris
>
> [1]https://github.com/bbrezillon/linux/commits/nand/mlc

Thanks,
PrasannaKumar