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Date:   Thu, 9 Jan 2020 19:08:38 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Chuanhong Guo <gch981213@gmail.com>
Cc:     linux-mtd@lists.infradead.org,
        Boris Brezillon <bbrezillon@kernel.org>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mtd: nand: spi: rework detect procedure for different
 read id op
Message-ID: <20200109190838.7028c8d9@xps13>
In-Reply-To: <20200109075551.357179-1-gch981213@gmail.com>
References: <20200109075551.357179-1-gch981213@gmail.com>
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Hi Chuanhong,

Chuanhong Guo <gch981213@gmail.com> wrote on Thu,  9 Jan 2020 15:54:00
+0800:

> Currently there are 3 different variants of read_id implementation:
> 1. opcode only. Found in GD5FxGQ4xF.
> 2. opcode + 1 addr byte. Found in GD5GxGQ4xA/E
> 3. opcode + 1 dummy byte. Found in other currently supported chips.
> 
> Original implementation was for variant 1 and let detect function
> of chips with variant 2 and 3 to ignore the first byte. This isn't
> robust:
> 
> 1. For chips of variant 2, if SPI master doesn't keep MOSI low
> during read, chip will get a random id offset, and the entire id
> buffer will shift by that offset, causing detect failure.
> 
> 2. For chips of variant 1, if it happens to get a devid that equals
> to manufacture id of variant 2 or 3 chips, it'll get incorrectly
> detected.
> 
> This patch reworks detect procedure to address problems above. New
> logic do detection for all variants separatedly, in 1-2-3 order.
> Since all current detect methods do exactly the same id matching
> procedure, unify them into core.c and remove detect method from
> manufacture_ops.
> 
> Tested on GD5F1GQ4UAYIG and W25N01GVZEIG.
> 
> Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
> ---
>  drivers/mtd/nand/spi/core.c       | 89 +++++++++++++++++++++++--------
>  drivers/mtd/nand/spi/gigadevice.c | 46 ++++++----------
>  drivers/mtd/nand/spi/macronix.c   | 25 ++-------
>  drivers/mtd/nand/spi/micron.c     | 24 ++-------
>  drivers/mtd/nand/spi/paragon.c    | 23 ++------
>  drivers/mtd/nand/spi/toshiba.c    | 25 ++-------
>  drivers/mtd/nand/spi/winbond.c    | 29 ++--------
>  include/linux/mtd/spinand.h       | 24 ++++-----
>  8 files changed, 110 insertions(+), 175 deletions(-)

Nice diffstat, and nice implementation IMHO.

I'm fine with the patch but I would love to hear Boris' voice on this.

Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>

One minor nit below.


> @@ -215,15 +204,22 @@ struct spinand_manufacturer_ops {
>   * struct spinand_manufacturer - SPI NAND manufacturer instance
>   * @id: manufacturer ID
>   * @name: manufacturer name
> + * @devid_len: number of bytes in device ID
> + * @spinand_table: array with info for spi nands under current manufacturer

This description is not very clear to me.
And also s/spi nands/SPI-NANDs/

> + * @nchips: number of chips available in spinand_table
>   * @ops: manufacturer operations
>   */
>  struct spinand_manufacturer {
>  	u8 id;
>  	char *name;
> +	u8 devid_len;
> +	const struct spinand_info *spinand_table;
> +	size_t nchips;
>  	const struct spinand_manufacturer_ops *ops;
>  };
>  
>  /* SPI NAND manufacturers */
> +extern const struct spinand_manufacturer gigadevice_spinand_manufacturer_1a_id;
>  extern const struct spinand_manufacturer gigadevice_spinand_manufacturer;
>  extern const struct spinand_manufacturer macronix_spinand_manufacturer;
>  extern const struct spinand_manufacturer micron_spinand_manufacturer;

Thanks,
Miquèl