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

Miquel Raynal
2019-03-12T10:28:18Z

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.

Thanks,
Miquèl