Re: [PATCH v3 2/9] mtd: rawnand: denali: refactor syndrome layout handling for raw access

Masahiro Yamada
2019-03-12T10:52:07Z

On Tue, Mar 12, 2019 at 7:28 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
> Hi Masahiro,
>
> Masahiro Yamada <yamada.masahiro@socionext.com> wrote on Tue, 12 Mar
> 2019 17:44:43 +0900:
>
> > The Denali IP adopts the syndrome page layout (payload and ECC are
> > interleaved). The *_page_raw() and *_oob() callbacks are complicated
> > because they must hide the underlying layout used by the hardware,
> > and always return contiguous in-band and out-of-band data.
> >
> > Currently, similar code is duplicated to reorganize the data layout.
> > For example, denali_read_page_raw() and denali_write_page_raw() look
> > almost the same.
> >
> > The idea for refactoring is to split the code into two parts:
> > [1] conversion of page layout
> > [2] what to do at every ECC chunk boundary
> >
> > For [1], I wrote denali_raw_payload_op() and denali_raw_oob_op().
> > They manipulate data for the Denali controller's specific page layout
> > of in-band, out-of-band, respectively.
> >
> > The difference between write and read is just the operation at
> > ECC chunk boundaries. For example, denali_read_oob() calls
> > nand_change_read_column_op(), whereas denali_write_oob() calls
> > nand_change_write_column_op(). So, I implemented [2] as a callback
> > passed into [1].
> >
> > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> > ---
> >
>
> [...]
>
> > static int denali_read_page_raw(struct nand_chip *chip, uint8_t *buf,
> > int oob_required, int page)
> > {
> > + struct denali_nand_info *denali = to_denali(chip);
> > struct mtd_info *mtd = nand_to_mtd(chip);
> > - struct denali_nand_info *denali = mtd_to_denali(mtd);
> > - int writesize = mtd->writesize;
> > - int oobsize = mtd->oobsize;
> > - int ecc_steps = chip->ecc.steps;
> > - int ecc_size = chip->ecc.size;
> > - int ecc_bytes = chip->ecc.bytes;
> > void *tmp_buf = denali->buf;
> > - int oob_skip = denali->oob_skip_bytes;
> > - size_t size = writesize + oobsize;
> > - int ret, i, pos, len;
> > + size_t size = mtd->writesize + mtd->oobsize;
> > + int ret;
> > +
> > + if (!buf)
> > + return -EINVAL;
> >
> > ret = denali_data_xfer(chip, tmp_buf, size, page, 1, 0);
> > if (ret)
> > return ret;
> >
> > - /* Arrange the buffer for syndrome payload/ecc layout */
> > - if (buf) {
> > - for (i = 0; i < ecc_steps; i++) {
> > - pos = i * (ecc_size + ecc_bytes);
> > - len = ecc_size;
> > -
> > - if (pos >= writesize)
> > - pos += oob_skip;
> > - else if (pos + len > writesize)
> > - len = writesize - pos;
> > -
> > - memcpy(buf, tmp_buf + pos, len);
> > - buf += len;
> > - if (len < ecc_size) {
> > - len = ecc_size - len;
> > - memcpy(buf, tmp_buf + writesize + oob_skip,
> > - len);
> > - buf += len;
> > - }
> > - }
> > - }
> > + ret = denali_raw_payload_op(chip, buf, denali_memcpy_in, tmp_buf);
>
> Honestly, I still don't like passing denali_memcpy_in/out as parameter.
>
> Besides that, once you'll have added helpers to avoid abusing the
> ternary operator in 4/9, the rest looks fine by me.
>

Do you have any suggestion?

There are 4 callbacks depending on the combination
of full-raw/oob, read/write.

I do not know how to make it cleaner.

--
Best Regards
Masahiro Yamada