Re: [PATCH v2 9/9] mtd: rawnand: jz4780-bch: Add support for the JZ4740

Boris Brezillon
2019-02-03T15:07:27Z

On Sun, 03 Feb 2019 11:56:32 -0300
Paul Cercueil <paul@crapouillou.net> wrote:

> Le dim. 3 févr. 2019 à 11:16, Boris Brezillon <bbrezillon@kernel.org>
> a écrit :
> > On Sun, 03 Feb 2019 10:58:13 -0300
> > Paul Cercueil <paul@crapouillou.net> wrote:
> >
> >> Le dim. 3 févr. 2019 à 4:35, Boris Brezillon
> >> <bbrezillon@kernel.org>
> >> a écrit :
> >> > On Sat, 2 Feb 2019 20:19:26 -0300
> >> > Paul Cercueil <paul@crapouillou.net> wrote:
> >> >
> >> >> Add the backend code for the jz4780-bch driver to support the
> >> JZ4740
> >> >> SoC from Ingenic.
> >> >>
> >> >> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> >> >> ---
> >> >>
> >> >> Changes:
> >> >>
> >> >> v2: New patch
> >> >>
> >> >> drivers/mtd/nand/raw/ingenic/Makefile | 2 +-
> >> >> drivers/mtd/nand/raw/ingenic/jz4740_bch.c | 173
> >> >> ++++++++++++++++++
> >> >> .../mtd/nand/raw/ingenic/jz4780_bch_common.c | 1 +
> >> >> .../nand/raw/ingenic/jz4780_bch_internal.h | 1 +
> >> >> 4 files changed, 176 insertions(+), 1 deletion(-)
> >> >> create mode 100644 drivers/mtd/nand/raw/ingenic/jz4740_bch.c
> >> >>
> >> >> diff --git a/drivers/mtd/nand/raw/ingenic/Makefile
> >> >> b/drivers/mtd/nand/raw/ingenic/Makefile
> >> >> index f38b467490cf..d16c96113a93 100644
> >> >> --- a/drivers/mtd/nand/raw/ingenic/Makefile
> >> >> +++ b/drivers/mtd/nand/raw/ingenic/Makefile
> >> >> @@ -1,3 +1,3 @@
> >> >> obj-$(CONFIG_MTD_NAND_JZ4740) += jz4740_nand.o
> >> >> obj-$(CONFIG_MTD_NAND_JZ4780) += jz4780_nand.o
> >> jz4780_bch_common.o
> >> >> \
> >> >> - jz4780_bch.o jz4725b_bch.o
> >> >> + jz4780_bch.o jz4725b_bch.o jz4740_bch.o
> >> >
> >> > I still don't see the point of the jz4780_bch_common/jz47xxx_bch
> >> > separation. You seem to always embed all objects anyway, so you
> >> can
> >> > just put the code for both engines in the same source file and
> >> decide
> >> > which one to use based on the compat (which you already do
> >> anyway).
> >>
> >> Each SoC has a different set of registers for the BCH hardware. I
> >> can
> >> try to
> >> cram everything into one file, but it won't be that much cleaner.
> >
> > Then maybe they deserve separate drivers/modules.
> >
> > BTW, didn't you say that one IP uses Reed-Salomon instead of BCH. I'd
> > suggest prefixing structs and functions with jz47xx_ecc instead of
> > jz47xx_bch and naming the common part jz47xx_ecc.c to reflect that.
>
> Would it be a good idea to make a generic ECC API that the jz47xx_nand
> driver could use? Then the three jz47xx BCH codepaths could be separate
> drivers that register with the generic ECC core.

Definitely. Actually, Miquel is already working on that, but I don't
think it's a good idea to wait for this new framework to be finished to
get your changes merged. So I'd recommend having a jz specific ECC API
(pretty much the one you have in the common file expect it would be
prefixed with _ecc instead of _bch) and convert it to the generic
approach afterwards. Given the size of the common.c file, you can even
put everything in jz47xx_ecc.h as inline funcs to avoid having yet
another module.