From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Boris Brezillon <bbrezillon@kernel.org>,
Richard Weinberger <richard@nod.at>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Marek Vasut <marek.vasut@gmail.com>,
linux-mtd <linux-mtd@lists.infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH v2 02/10] mtd: rawnand: denali: refactor syndrome layout handling for raw access
Date: Tue, 5 Mar 2019 18:55:00 +0100 [thread overview]
Message-ID: <20190305184929.7f0bc93b@xps13> (raw)
In-Reply-To: <CAK7LNASeBDxsUj2fu0bh9G6dXV2jxeHp6iBG+8FytNbHGtVHKQ@mail.gmail.com>
Hi Masahiro,
Masahiro Yamada <yamada.masahiro@socionext.com> wrote on Tue, 5 Mar
2019 18:20:22 +0900:
> Hi Miquel,
>
> On Mon, Mar 4, 2019 at 6:01 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >
> > Hi Masahiro,
> >
> > Masahiro Yamada <yamada.masahiro@socionext.com> wrote on Tue, 12 Feb
> > 2019 16:12:54 +0900:
> >
> > > The Denali IP adopts the syndrome page layout (payload and ECC are
> > > interleaved). The *_page_raw() and *_oob() callbacks are complicated
> > > because they must hide the underlying layout used by the hardware,
> > > and always return contiguous in-band and out-of-band data.
> > >
> > > Currently, similar code is duplicated to reorganize the data layout.
> > > For example, denali_read_page_raw() and denali_write_page_raw() look
> > > almost the same.
> > >
> > > The idea for refactoring is to split the code into two parts:
> > > [1] conversion of page layout
> > > [2] what to do at every ECC chunk boundary
> > >
> > > For [1], I wrote denali_raw_payload_op() and denali_raw_oob_op().
> > > They manipulate data for the Denali controller's specific page layout
> > > of in-band, out-of-band, respectively.
> >
> > Could you please comment the purpose of these two functions in the code
> > as well?
>
>
> OK, I will.
>
>
>
> > >
> > > The difference between write and read is just the operation at
> > > ECC chunk boundaries. For example, denali_read_oob() calls
> > > nand_change_read_column_op(), whereas denali_write_oob() calls
> > > nand_change_write_column_op(). So, I implemented [2] as a callback
> > > passed into [1].
> > >
> > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> > > ---
> > >
> > > Changes in v2: None
> > >
> > > drivers/mtd/nand/raw/denali.c | 354 +++++++++++++++++++-----------------------
> > > 1 file changed, 163 insertions(+), 191 deletions(-)
> >
> > Too bad that the size of the driver did not shrink more than that :)
>
> Indeed, less than expected.
>
> But, please do not miss this commit is adding
> error check to every operation.
>
> Prior to this commit, the code just ignored the return code
> because 97d90da8a886949f simply replaced old hooks
> despite the new ones return the error code.
>
>
> Generally, every error check costs two lines
> in the following form:
>
>
> ret = (do something)
> if (ret)
> return ret;
>
Right!
>
>
> > > +
> > > +static int denali_memcpy_in(void *buf, unsigned int offset, unsigned int len,
> > > + void *priv)
> > > +{
> > > + memcpy(buf, priv + offset, len);
> > > + return 0;
> > > }
> >
> > Maybe this "callback" and the (_out cousin) could be part of you
> > controller's structure,
> > and you could use a read/write flag instead of
> > passing the functions' pointer?
>
> This is what the old code does.
>
> There are 4 callbacks for the combination
> of raw/oob, and write/read.
>
> I do not know how your suggestion looks like,
> and whether it will make the code cleaner.
>
Please give it a try!
Thanks,
Miquèl
next prev parent reply other threads:[~2019-03-05 17:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 7:12 [PATCH v2 00/10] mtd: rawnand: denali: exec_op(), controller/chip separation, and cleanups Masahiro Yamada
2019-02-12 7:12 ` [PATCH v2 01/10] mtd: rawnand: denali: use nand_chip pointer more for internal functions Masahiro Yamada
2019-02-12 7:12 ` [PATCH v2 02/10] mtd: rawnand: denali: refactor syndrome layout handling for raw access Masahiro Yamada
2019-03-04 9:01 ` Miquel Raynal
2019-03-05 9:20 ` Masahiro Yamada
2019-03-05 17:55 ` Miquel Raynal [this message]
2019-02-12 7:12 ` [PATCH v2 03/10] mtd: rawnand: denali: remove unneeded casts in denali_{read,write}_pio Masahiro Yamada
2019-02-12 7:12 ` [PATCH v2 04/10] mtd: rawnand: denali: switch over to ->exec_op() from legacy hooks Masahiro Yamada
2019-03-04 9:30 ` Miquel Raynal
2019-03-05 7:13 ` Masahiro Yamada
2019-02-12 7:12 ` [PATCH v2 05/10] mtd: rawnand: denali: use more precise timeout for NAND_OP_WAITRDT_INSTR Masahiro Yamada
2019-03-04 8:43 ` Miquel Raynal
2019-03-05 6:36 ` Masahiro Yamada
2019-02-12 7:12 ` [PATCH v2 06/10] mtd: rawnand: denali: use bool type instead of int where appropriate Masahiro Yamada
2019-02-12 7:12 ` [PATCH v2 07/10] mtd: rawnand: denali_pci: rename goto labels Masahiro Yamada
2019-02-12 7:13 ` [PATCH v2 08/10] mtd: rawnand: denali: decouple controller and NAND chips Masahiro Yamada
2019-02-18 20:01 ` Rob Herring
2019-02-12 7:13 ` [PATCH v2 09/10] mtd: rawnand: denali: remove DENALI_NR_BANKS macro Masahiro Yamada
2019-02-12 7:13 ` [PATCH v2 10/10] mtd: rawnand: denali: clean up coding style Masahiro Yamada
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