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

Miquel Raynal
2020-01-21T13:40:39Z

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<---

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

Thanks,
Miquèl