Date:   Mon, 19 Aug 2019 08:51:52 +0000
From:   "Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@...ron.com>
To:     Miquel Raynal <miquel.raynal@...tlin.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>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jeff Kletsky <git-commits@...ycomm.com>,
        Chuanhong Guo <gch981213@...il.com>,
        liaoweixiong <liaoweixiong@...winnertech.com>
Subject: RE: [EXT] Re: [PATCH 4/8] mtd: spinand: enabled parameter page
 support

Hi Miquel,

> 
> 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.

Okay, I will create separate patch for fixup function.

> 
> >
> > 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.
> 

Sorry for the inconvenience caused, I will take care from next time.

> > + * @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.

okay.

> 
> > +		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.

okay, I will mention in kernel doc.

> 
> > +				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.

I have done this intentionally, because in raw NAND case there is function
"nand_read_data_op" called inside for-loop. I don't think just for if (i == 3) 
it is necessary to create new function.

Let me know if you have different opinion.

> 
> > +
> > +	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.

I will do it as per your suggestion.

> 
> > +				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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