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

["Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@xxxxxxxxxx>]

Hi Miquel,

> 
> Hi Shivamurthy,
> 
> "Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@xxxxxxxxxx> 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@xxxxxxxxx wrote on Sun, 19 Jan 2020 15:54:31 +0100:
> > >
> > > > From: Shivamurthy Shastri <sshivamurthy@xxxxxxxxxx>
> > > >
> > > > 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@xxxxxxxxxx>
> > > > ---
> > > >  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
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