Re: [RFC] NAND: Optimize NAND_ECC_HW_OOB_FIRST read

From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: "David Woodhouse" <dwmw2@infradead.org>,
	"Brian Norris" <computersforpeace@gmail.com>,
	"Marek Vašut" <marek.vasut@gmail.com>,
	cyrille.pitchen@wedev4u.fr, linux-mtd@lists.infradead.org,
	"open list" <linux-kernel@vger.kernel.org>,
	"Lars-Peter Clausen" <lars@metafoo.de>
Subject: Re: [RFC] NAND: Optimize NAND_ECC_HW_OOB_FIRST read
Date: Mon, 30 Oct 2017 19:04:18 +0530	[thread overview]
Message-ID: <CANc+2y5QWNSRf_-oOuU8TYbyVHYrbPqK8+gO=Y56-MMaJp+nZQ@mail.gmail.com> (raw)
In-Reply-To: <20171030140351.16cb4461@bbrezillon>

Hi Boris,

On 30 October 2017 at 18:33, Boris Brezillon
<boris.brezillon@free-electrons.com> wrote:
> On Mon, 30 Oct 2017 18:17:50 +0530
> PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> wrote:
>
>> Hi Boris,
>>
>> On 30 October 2017 at 14:04, Boris Brezillon
>> <boris.brezillon@free-electrons.com> wrote:
>> > Hi PrasannaKumar,
>> >
>> > On Sat, 28 Oct 2017 13:13:51 +0530
>> > PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> wrote:
>> >
>> >> From: Lars-Peter Clausen <lars@metafoo.de>
>> >>
>> >> Avoid sending unnecessary READ commands to the chip.
>> >>
>> >> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
>> >> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
>> >> ---
>> >> This patch is taken from git://projects.qi-hardware.com/qi-kernel.git
>> >> branch jz-3.16. From [1] and [2] it can be seen that the patch author
>> >> thinks this can be sent upstream but it never happened so far. This
>> >> patch is used in OpenWRT as seen from [3].
>> >
>> > Sounds reasonable, but it's likely to conflict with something I'd like
>> > to queue for 4.16 [1]. I'll rebase this patch on nand/next once the
>> > ->exec_op() series is merged. Don't hesitate to ping me if I forget.
>> >
>> > Regards,
>> >
>> > Boris
>> >
>> > [1]http://patchwork.ozlabs.org/project/linux-mtd/list/?series=8923
>>
>> Okay. I will remind you if required.
>>
>> There is another patch used in OpenWRT at [1]. Do you mind to have a
>> look at it and take that if it is useful? I don't see a point in me
>> sending it as a RFC as I am not contributing anything to it other than
>> noticing its existence.
>
> Yep, it makes sense to have that one applied too, but this is pretty
> much the same problem: it will conflict with the ->exec_op() rework.

True. I did realise that.

> Can you please send it to the ML so I can track it in patchwork and

Sure.

> respin it when ->exec_op() is out. I'll also need someone owning a HW
> using NAND_ECC_HW_OOB_FIRST to test the changes. Do you have such HW?

I am looking at OpenWRT and trying to post patches that I feel useful.
I do not have access to JZ4740.

Grepping over driver/mtd/nand I can find that only JZ4740 and DaVinci
supports this. When I last searched I could not find people with
access to Ingenic JZ4740 SoC (which is targeted by arch/mips/xburst in
OpenWRT). I can check with people who have newer SoC from Ingenic if
that has the required hardware.

Please let me know how to test that patch if I could find someone who
can test that patch.

Thanks,
PrasannaKumar