RE: [EXT] Re: [PATCH 4/8] mtd: spinand: enabled parameter page support

[Shivamurthy Shastri (sshivamurthy)]

Hello Miquel & Boris,

Just a gentle reminder that I'd like some feedback.

Thanks,
Shiva

> 
> Hi Boris,
> 
> Another question for you :)
> 
> "Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@xxxxxxxxxx> wrote
> on
> Mon, 19 Aug 2019 08:51:52 +0000:
> 
> > Hi Miquel,
> >
> > >
> > > Hi Shiva,
> > >
> > > shiva.linuxworks@xxxxxxxxx wrote on Mon, 22 Jul 2019 07:56:17 +0200:
> > >
> > > "mtd: spinand: enable parameter page support"
> > >
> > > > From: Shivamurthy Shastri <sshivamurthy@xxxxxxxxxx>
> > > >
> > > > 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@xxxxxxxxxx>
> > > > ---
> > > >  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.
> 
> I don't have a strong opinion on that. Boris what do you think? Shall
> we duplicate the code? It's not just about the if condition, it's the
> whole for loop which is very similar.
> 
> 
> Thanks,
> MiquÃl