RE: [EXT] Re: [PATCH 3/4] mtd: spinand: Add M70A series Micron SPI NAND devices

Shivamurthy Shastri (sshivamurthy)
2020-01-21T14:59:17Z

Hi Miquel,

>
> Hi Shivamurthy,
>
> "Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@micron.com> wrote
> on
> Tue, 21 Jan 2020 12:23:20 +0000:
>
> > Hi Miquel,
> >
> > >
> > > Hi Shiva,
> > >
> > > This is remark common to the four patches: you miss the 'v2' prefix in
> > > the object.
> > >
> >
> > Sorry for this mistake.
> > I recognized this after sending out the patches.
> >
> > > shiva.linuxworks@gmail.com wrote on Sun, 19 Jan 2020 15:54:31 +0100:
> > >
> > > > From: Shivamurthy Shastri <sshivamurthy@micron.com>
> > > >
> > > > Add device table for M70A series Micron SPI NAND devices.
> > > >
> > > > While at it, disable the Continuous Read feature which is enabled by
> > > > default.
> > >
> > > Can you please give us more detail on why this is an issue?
> >
> > "Continuous Read" is the new feature added by the Micron for
> > M70A series devices. If this feature is enabled, the READ command
> > doesn't output the OOB area. The following short description
> > describes this feature.
> >
> > Description:
> > If the Continuous Read feature is enabled, the device provides
> > the capability to read the whole block with a single command.
> > However, the read command doesn't output the OOB area.
> >
> > Read command behavior (if Continuous Read enabled):
> > The READ CACHE command doesn't require the starting column address.
> > The device always output the data starting from the first column of the
> > cache register, and once the end of the cache register reached, the data
> > output continues through the next page. With the continuous read mode,
> > it is possible to read out the entire block using a single READ command, and
> > once the end of the block reached, the output pins become High-Z state.
>
> Ok I understand better. In this case there is no need to split this
> commit, instead just reword the commit log to something like:
>
> --->8---
> Add device table for M70A series Micron SPI-NAND devices.
>
> As opposed to the M60A series already supported, M70A parts have the
> "Continuous Read" feature enabled by default which does not fit the
> subsystem needs.
>
> <here explain the feature>.
>
> Hence, we disable the feature at probe time.
> ---8<---
>

Sure, I will change as per your suggestion.

> However, below, you disable this bit for all the parts. Is this really
> ok? Souldn't we make it more specific to this series?

It is ok because this bit is unused in other series.

>
> >
> > >
> > > Shall we backport it to stable?
> >
> > This is not a bug fix and applicable only to M70A series devices, there is no
> > need to backport.
> > (FYI, the previously enabled device was M79A series)
> >
> > >
> > > As a rule of thumb, when you start a sentence by "while at it" in a
> > > commit message and this is not a trivial change : split the patch,
> > > please. Unless this is really related and in this case explain how and
> > > why in the commit message.
> >
> > Okay, I will explain in my next version.
> >
> > >
> > > >
> > > > Signed-off-by: Shivamurthy Shastri <sshivamurthy@micron.com>
> > > > ---
> > > > drivers/mtd/nand/spi/micron.c | 31
> > > +++++++++++++++++++++++++++++++
> > > > 1 file changed, 31 insertions(+)
> > > >
> > > > diff --git a/drivers/mtd/nand/spi/micron.c
> > > b/drivers/mtd/nand/spi/micron.c
> > > > index 5fd1f921ef12..45fc37c58f8a 100644
> > > > --- a/drivers/mtd/nand/spi/micron.c
> > > > +++ b/drivers/mtd/nand/spi/micron.c
> > > > @@ -131,6 +131,26 @@ static const struct spinand_info
> > > micron_spinand_table[] = {
> > > > 0,
> > > > SPINAND_ECCINFO(&micron_8_ooblayout,
> > > > micron_8_ecc_get_status)),
> > > > + /* M70A 4Gb 3.3V */
> > > > + SPINAND_INFO("MT29F4G01ABAFD", 0x34,
> > > > + NAND_MEMORG(1, 4096, 256, 64, 2048, 40, 1, 1, 1),
> > > > + NAND_ECCREQ(8, 512),
> > > > + SPINAND_INFO_OP_VARIANTS(&read_cache_variants,
> > > > + &write_cache_variants,
> > > > + &update_cache_variants),
> > > > + 0,
> > > > + SPINAND_ECCINFO(&micron_8_ooblayout,
> > > > + micron_8_ecc_get_status)),
> > > > + /* M70A 4Gb 1.8V */
> > > > + SPINAND_INFO("MT29F4G01ABBFD", 0x35,
> > > > + NAND_MEMORG(1, 4096, 256, 64, 2048, 40, 1, 1, 1),
> > > > + NAND_ECCREQ(8, 512),
> > > > + SPINAND_INFO_OP_VARIANTS(&read_cache_variants,
> > > > + &write_cache_variants,
> > > > + &update_cache_variants),
> > > > + 0,
> > > > + SPINAND_ECCINFO(&micron_8_ooblayout,
> > > > + micron_8_ecc_get_status)),
> > > > };
> > > >
> > > > static int micron_spinand_detect(struct spinand_device *spinand)
> > > > @@ -153,8 +173,19 @@ static int micron_spinand_detect(struct
> > > spinand_device *spinand)
> > > > return 1;
> > > > }
> > > >
> > > > +static int micron_spinand_init(struct spinand_device *spinand)
> > > > +{
> > > > + /*
> > > > + * M70A device series enable Continuous Read feature at Power-up,
> > > > + * which is not supported. Disable this bit to avoid any possible
> > > > + * failure.
> > > > + */
> > > > + return spinand_upd_cfg(spinand, CFG_QUAD_ENABLE, 0);
> > > > +}
> > > > +
> > > > static const struct spinand_manufacturer_ops
> > > micron_spinand_manuf_ops = {
> > > > .detect = micron_spinand_detect,
> > > > + .init = micron_spinand_init,
> > > > };
> > > >
> > > > const struct spinand_manufacturer micron_spinand_manufacturer = {
> > >

Thanks,
Shiva