linux-kernel - Re: [PATCH v3 4/5] mtd: spinand: micron: Add M70A series Micron SPI NAND devices

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Message-ID: <20200205105422.57b5f6c4@xps13>
Date:   Wed, 5 Feb 2020 10:54:22 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     shiva.linuxworks@...il.com
Cc:     Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Shivamurthy Shastri <sshivamurthy@...ron.com>
Subject: Re: [PATCH v3 4/5] mtd: spinand: micron: Add M70A series Micron SPI
 NAND devices

Hi shiva.linuxworks@...il.com,

shiva.linuxworks@...il.com wrote on Sun,  2 Feb 2020 22:55:07 +0100:

> From: Shivamurthy Shastri <sshivamurthy@...ron.com>
> 
> Add device table for M70A series Micron SPI NAND devices.
> 
> As opposed to the M79A and M78A series already supported, M70A parts
> have the "Continuous Read" feature enabled by default, which does not fit
> the subsystem needs.
> 
> In this mode, 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. However, during this mode the read command
> doesn't output the OOB area.
> 
> Hence, we disable the feature at probe time.
> 
> Signed-off-by: Shivamurthy Shastri <sshivamurthy@...ron.com>
> ---
>  drivers/mtd/nand/spi/micron.c | 36 +++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/drivers/mtd/nand/spi/micron.c b/drivers/mtd/nand/spi/micron.c
> index 5fd1f921ef12..3d3734afc35e 100644
> --- a/drivers/mtd/nand/spi/micron.c
> +++ b/drivers/mtd/nand/spi/micron.c
> @@ -18,6 +18,8 @@
>  #define MICRON_STATUS_ECC_4TO6_BITFLIPS	(3 << 4)
>  #define MICRON_STATUS_ECC_7TO8_BITFLIPS	(5 << 4)
>  
> +#define MICRON_CFG_CONTI_READ		BIT(0)
> +
>  static SPINAND_OP_VARIANTS(read_cache_variants,
>  		SPINAND_PAGE_READ_FROM_CACHE_QUADIO_OP(0, 2, NULL, 0),
>  		SPINAND_PAGE_READ_FROM_CACHE_X4_OP(0, 1, NULL, 0),
> @@ -131,6 +133,26 @@ 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),
> +		     SPINAND_HAS_CR_FEAT_BIT,
> +		     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),
> +		     SPINAND_HAS_CR_FEAT_BIT,
> +		     SPINAND_ECCINFO(&micron_8_ooblayout,
> +				     micron_8_ecc_get_status)),
>  };
>  
>  static int micron_spinand_detect(struct spinand_device *spinand)
> @@ -153,8 +175,22 @@ 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.
> +	 */
> +	if (spinand->flags == SPINAND_HAS_CR_FEAT_BIT)
> +		return spinand_upd_cfg(spinand, MICRON_CFG_CONTI_READ, 0);
> +
> +	return 0;
> +}
> +
>  static const struct spinand_manufacturer_ops micron_spinand_manuf_ops = {
>  	.detect = micron_spinand_detect,
> +	.init = micron_spinand_init,
>  };

I would move the addition of .init = ... and the function definition to
patch 3/5.

The logic is:
1/ You introduce the feature
2/ You add support for new devices and use this feature

>  
>  const struct spinand_manufacturer micron_spinand_manufacturer = {

Otherwise looks good.

Thanks,
Miquèl