From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Abhishek Sahu <absahu@codeaurora.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Marek Vasut <marek.vasut@gmail.com>,
Richard Weinberger <richard@nod.at>,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mtd@lists.infradead.org, Andy Gross <andy.gross@linaro.org>
Subject: Re: [PATCH 2/5] mtd: rawnand: qcom: remove driver specific block_markbad function
Date: Fri, 20 Jul 2018 15:03:48 +0200 [thread overview]
Message-ID: <20180720150348.592c8984@bbrezillon> (raw)
In-Reply-To: <7ab0be154272b71f9beb2a7fb830c7be@codeaurora.org>
On Fri, 20 Jul 2018 17:46:38 +0530
Abhishek Sahu <absahu@codeaurora.org> wrote:
> Hi Boris,
>
> On 2018-07-19 03:13, Boris Brezillon wrote:
> > On Wed, 18 Jul 2018 23:23:50 +0200
> > Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >
> >> Boris,
> >>
> >> Can you please check the change in qcom_nandc_write_oob() is
> >> valid? I think it is but as this is a bit of a hack I prefer double
> >> checking.
> >
> > Indeed, it's hack-ish.
> >
> >>
> >> Thanks,
> >> Miquèl
> >>
> >>
> >> Abhishek Sahu <absahu@codeaurora.org> wrote on Fri, 6 Jul 2018
> >> 13:21:56 +0530:
> >>
> >> > The NAND base layer calls write_oob() by setting bytes at
> >> > chip->badblockpos with value non 0xFF for updating bad block status.
> >> > The QCOM NAND controller skips the bad block bytes while doing normal
> >> > write with ECC enabled. When initial support for this driver was
> >> > added, the driver specific function was added temporarily for
> >> > block_markbad() with assumption to change for raw read in NAND base
> >> > layer. Moving to raw read for block_markbad() seems to take more time
> >> > so this patch removes driver specific block_markbad() function by
> >> > using following HACK in write_oob() function.
> >> >
> >> > Check for BBM bytes in OOB and accordingly do raw write for updating
> >> > BBM bytes in NAND flash or normal write for updating available OOB
> >> > bytes.
> >
> > Why don't we change that instead of patching the qcom driver to guess
> > when the core tries to mark a block bad? If you're afraid of breaking
> > existing drivers that might rely on the "write/read BBM in non-raw
> > mode" solution (I'm sure some drivers are), you can always add a new
> > flag in chip->options (NAND_ACCESS_BBM_IN_RAW_MODE) and only use raw
> > accessors when this flag is set.
> >
>
> We started with that Only
>
> http://patchwork.ozlabs.org/patch/508565/
>
> and since we didn't conclude, we went for driver
> specific bad block check and mark bad block functions.
>
> Now, we wanted to get rid of driver specific functions
>
> 1. For bad block check, we found the way to get the BBM bytes
> with ECC read. Controller updates BBM in separate register
> which we can read and update the same in OOB. Patch #1 of
> series does the same.
>
> 2. For bad block mark, there is no way to update in ECC mode
> that's why we went for HACK to get rid of driver specific
> function.
>
> If adding flag is fine now then this HACK won't be required.
Yep. I'm fine with that. Can you rebase the patch you pointed out on top
of nand/next and move the flag to chip->options instead of
chip->bbt_options + prefix it with NAND_ instead of NAND_BBT_?
> Moving to RAW mode for every one still looks risky.
I agree.
next prev parent reply other threads:[~2018-07-20 13:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-06 7:51 [PATCH 0/5] Update for removing driver specific BBM functions Abhishek Sahu
2018-07-06 7:51 ` [PATCH 1/5] mtd: rawnand: qcom: remove driver specific bad block check function Abhishek Sahu
2018-07-06 7:51 ` [PATCH 2/5] mtd: rawnand: qcom: remove driver specific block_markbad function Abhishek Sahu
2018-07-18 21:23 ` Miquel Raynal
2018-07-18 21:43 ` Boris Brezillon
2018-07-20 12:16 ` Abhishek Sahu
2018-07-20 13:03 ` Boris Brezillon [this message]
2018-11-04 15:56 ` Boris Brezillon
2018-11-09 6:18 ` Abhishek Sahu
2018-07-06 7:51 ` [PATCH 3/5] mtd: rawnand: qcom: fix NAND register write errors Abhishek Sahu
2018-07-06 7:51 ` [PATCH 4/5] mtd: rawnand: qcom: update BBT related flags Abhishek Sahu
2018-07-18 21:15 ` Miquel Raynal
2018-07-18 21:36 ` Boris Brezillon
2018-07-18 21:41 ` Miquel Raynal
2018-07-18 21:42 ` Miquel Raynal
2018-07-20 7:14 ` Abhishek Sahu
2018-07-06 7:51 ` [PATCH 5/5] mtd: rawnand: qcom: reorganization by removing read/write helpers Abhishek Sahu
2018-07-18 21:29 ` Miquel Raynal
2018-07-18 21:54 ` Boris Brezillon
2018-07-28 10:20 ` Abhishek Sahu
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