Date:   Wed, 7 Aug 2019 11:48:55 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     shiva.linuxworks@...il.com
Cc:     Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        Shivamurthy Shastri <sshivamurthy@...ron.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jeff Kletsky <git-commits@...ycomm.com>,
        Chuanhong Guo <gch981213@...il.com>,
        liaoweixiong <liaoweixiong@...winnertech.com>
Subject: Re: [PATCH 4/8] mtd: spinand: enabled parameter page support

Hi Shiva,

shiva.linuxworks@...il.com wrote on Mon, 22 Jul 2019 07:56:17 +0200:

"mtd: spinand: enable parameter page support"

> From: Shivamurthy Shastri <sshivamurthy@...ron.com>
> 
> Some of the SPI NAND devices has parameter page, which is similar to
                 -             have a
> ONFI table.
  regular raw NAND ONFI tables.

> 
> But, it may not be self sufficient to propagate all the required
  As it may not be
> parameters. Fixup function has been added in struct manufacturer to
            , a fixup        is being added in the manufacturer structure
> accommodate this.

The fixup function sentence should be dropped from the commit message,
see below.

> 
> Signed-off-by: Shivamurthy Shastri <sshivamurthy@...ron.com>
> ---
>  drivers/mtd/nand/spi/core.c | 134 ++++++++++++++++++++++++++++++++++++
>  include/linux/mtd/spinand.h |   3 +
>  2 files changed, 137 insertions(+)
> 
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 89f6beefb01c..7ae76dab9141 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -400,6 +400,131 @@ static int spinand_lock_block(struct spinand_device *spinand, u8 lock)
>  	return spinand_write_reg_op(spinand, REG_BLOCK_LOCK, lock);
>  }
>  
> +/**
> + * spinand_read_param_page_op - Read parameter page operation

Again, the name in the doc does not fit the function you describe

> + * @spinand: the spinand
                    SPI-NAND chip

Shiva, there are way too much typos and shortcuts in your series.
Please be more careful otherwise we can't focus on the technical
aspects. I am not a native English speaker at all but please, plain
English is not C code. We talk SPI-NAND and not spinand, we say
structure and not struct, acronyms are uppercase, etc.

> + * @page: page number where parameter page tables can be found
                              ^ the
> + * @buf: buffer used to store the parameter page
> + * @len: length of the buffer
> + *
> + * Read parameter page
          the
> + *
> + * Returns 0 on success, a negative error code otherwise.
> + */
> +static int spinand_parameter_page_read(struct spinand_device *spinand,
> +				       u8 page, void *buf, unsigned int len)
> +{
> +	struct spi_mem_op pread_op = SPINAND_PAGE_READ_OP(page);
> +	struct spi_mem_op pread_cache_op =
> +				SPINAND_PAGE_READ_FROM_CACHE_OP(false,
> +								0,
> +								1,
> +								buf,
> +								len);

That's ok if you cross the 80 characters boundary here. You may put "0,
1," on the first line and "buf, len);" on the second.

> +	u8 feature;
> +	u8 status;
> +	int ret;
> +
> +	if (len && !buf)
> +		return -EINVAL;
> +
> +	ret = spinand_read_reg_op(spinand, REG_CFG,
> +				  &feature);
> +	if (ret)
> +		return ret;
> +
> +	/* CFG_OTP_ENABLE is used to enable parameter page access */
> +	feature |= CFG_OTP_ENABLE;
> +
> +	spinand_write_reg_op(spinand, REG_CFG, feature);
> +
> +	ret = spi_mem_exec_op(spinand->spimem, &pread_op);
> +	if (ret)
> +		return ret;
> +
> +	ret = spinand_wait(spinand, &status);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = spi_mem_exec_op(spinand->spimem, &pread_cache_op);
> +	if (ret)
> +		return ret;
> +
> +	ret = spinand_read_reg_op(spinand, REG_CFG,
> +				  &feature);
> +	if (ret)
> +		return ret;
> +
> +	feature &= ~CFG_OTP_ENABLE;
> +
> +	spinand_write_reg_op(spinand, REG_CFG, feature);
> +
> +	return 0;
> +}
> +
Add the kernel doc please

Change the below function so that it returns 1 if the page was
detected, 0 if it did not, an negative error code otherwise.

> +static int spinand_param_page_detect(struct spinand_device *spinand)
> +{
> +	struct mtd_info *mtd = spinand_to_mtd(spinand);
> +	struct nand_memory_organization *memorg;
> +	struct nand_onfi_params *p;
> +	struct nand_device *base = spinand_to_nand(spinand);
> +	int i, ret;
> +
> +	memorg = nanddev_get_memorg(base);
> +
> +	/* Allocate buffer to hold parameter page */
> +	p = kzalloc((sizeof(*p) * 3), GFP_KERNEL);
> +	if (!p)
> +		return -ENOMEM;
> +
> +	ret = spinand_parameter_page_read(spinand, 0x01, p, sizeof(*p) * 3);
> +	if (ret) {
> +		ret = 0;

No, you should return the error in case of error. You will later handle
the fact that there is no parameter page.

> +		goto free_param_page;
> +	}
> +
> +	for (i = 0; i < 3; i++) {
> +		if (onfi_crc16(ONFI_CRC_BASE, (u8 *)&p[i], 254) ==
                                                           ^
If you force the parameter page to be 254 bytes long it means you limit
yourself to ONFI standard. That's not a problem, but then you should
mention it in the function name.

> +				le16_to_cpu(p->crc)) {
> +			if (i)
> +				memcpy(p, &p[i], sizeof(*p));
> +			break;
> +		}
> +	}
> +
> +	if (i == 3) {
> +		const void *srcbufs[3] = {p, p + 1, p + 2};
> +
> +		pr_warn("Could not find a valid ONFI parameter page, trying bit-wise majority to recover it\n");
> +		nand_bit_wise_majority(srcbufs, ARRAY_SIZE(srcbufs), p,
> +				       sizeof(*p));
> +
> +		if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) !=
> +				le16_to_cpu(p->crc)) {
> +			pr_err("ONFI parameter recovery failed, aborting\n");
> +			goto free_param_page;
> +		}
> +	}

The whole for-loop and the if (i==3) condition is exactly the same as
for raw NANDs and must be extracted in a generic function:
1/ extract the function from nand/raw/nand_onfi.c and put it in
nand/onfi.c.
2/ then use it in this patch.

> +
> +	parse_onfi_params(memorg, p);
> +
> +	mtd->writesize = memorg->pagesize;
> +	mtd->erasesize = memorg->pages_per_eraseblock * memorg->pagesize;
> +	mtd->oobsize = memorg->oobsize;

This will be handled by nanddev_init, should be removed.

> +
> +	/* Manufacturers may interpret the parameter page differently */
> +	if (spinand->manufacturer->ops->fixup_param_page)
> +		spinand->manufacturer->ops->fixup_param_page(spinand, p);

The whole "manufacturer fixup" should be done separately.

> +
> +	/* Identification done, free the full parameter page and exit */
> +	ret = 1;
> +
> +free_param_page:
> +	kfree(p);
> +
> +	return ret;
> +}
> +
>  static int spinand_check_ecc_status(struct spinand_device *spinand, u8 status)
>  {
>  	struct nand_device *nand = spinand_to_nand(spinand);
> @@ -911,6 +1036,15 @@ static int spinand_detect(struct spinand_device *spinand)
>  		return ret;
>  	}
>  
> +	if (!spinand->base.memorg.pagesize) {
> +		ret = spinand_param_page_detect(spinand);
> +		if (ret <= 0) {
> +			dev_err(dev, "no parameter page for %*phN\n",

Not sure at this stage dev will give something meaningful. Anyway I
don't think we should scream at the user if his NAND is not an ONFI one
so please return an error only if ret < 0. If ret == 0 or ret == 1,
don't warn the user.

> +				SPINAND_MAX_ID_LEN, spinand->id.data);
> +			return -ENODEV;
> +		}
> +	}
> +
>  	if (nand->memorg.ntargets > 1 && !spinand->select_target) {
>  		dev_err(dev,
>  			"SPI NANDs with more than one die must implement ->select_target()\n");
> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
> index 4ea558bd3c46..fea820a20bc9 100644
> --- a/include/linux/mtd/spinand.h
> +++ b/include/linux/mtd/spinand.h
> @@ -15,6 +15,7 @@
>  #include <linux/mtd/nand.h>
>  #include <linux/spi/spi.h>
>  #include <linux/spi/spi-mem.h>
> +#include <linux/mtd/onfi.h>
>  
>  /**
>   * Standard SPI NAND flash operations
> @@ -209,6 +210,8 @@ struct spinand_manufacturer_ops {
>  	int (*detect)(struct spinand_device *spinand);
>  	int (*init)(struct spinand_device *spinand);
>  	void (*cleanup)(struct spinand_device *spinand);
> +	void (*fixup_param_page)(struct spinand_device *spinand,
> +				 struct nand_onfi_params *p);

Please do this in a separate patch.

>  };
>  
>  /**

Thanks,
Miquèl

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