Re: [PATCH v4 3/5] mtd: rawnand: meson: always read whole OOB bytes

Arseniy Krasnov
2023-05-23T17:32:29Z

On 22.05.2023 18:38, Miquel Raynal wrote:
> Hi Arseniy,
>
> AVKrasnov@sberdevices.ru wrote on Mon, 15 May 2023 12:44:37 +0300:
>
>> This changes size of read access to OOB area by reading all bytes of
>> OOB (free bytes + ECC engine bytes).
>
> This is normally up to the user (user in your case == jffs2). The
> controller driver should expose a number of user accessible bytes and
> then when users want the OOB area, they should access it entirely. On
> top of that read, they can extract (or "write only") the user bytes.

Sorry, I didn't get it. If driver exposes N bytes of user accessible bytes,
I must always return whole OOB yes? E.g. N + rest of OOB

>
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>> ---
>> drivers/mtd/nand/raw/meson_nand.c | 24 ++++++++++++++++++++++++
>> 1 file changed, 24 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
>> index 8526a6b87720..a31106c943d7 100644
>> --- a/drivers/mtd/nand/raw/meson_nand.c
>> +++ b/drivers/mtd/nand/raw/meson_nand.c
>> @@ -755,6 +755,30 @@ static int __meson_nfc_read_oob(struct nand_chip *nand, int page,
>> u32 oob_bytes;
>> u32 page_size;
>> int ret;
>> + int i;
>> +
>> + /* Read ECC codes and user bytes. */
>> + for (i = 0; i < nand->ecc.steps; i++) {
>> + u32 ecc_offs = nand->ecc.size * (i + 1) +
>> + NFC_OOB_PER_ECC(nand) * i;
>> +
>> + ret = nand_read_page_op(nand, page, 0, NULL, 0);
>> + if (ret)
>> + return ret;
>> +
>> + /* Use temporary buffer, because 'nand_change_read_column_op()'
>> + * seems work with some alignment, so we can't read data to
>> + * 'oob_buf' directly.
>
> DMA?

Yes I guess, this address passed to exec_op code and used as DMA.

>
>> + */
>> + ret = nand_change_read_column_op(nand, ecc_offs, meson_chip->oob_buf,
>> + NFC_OOB_PER_ECC(nand), false);
>> + if (ret)
>> + return ret;
>> +
>> + memcpy(oob_buf + i * NFC_OOB_PER_ECC(nand),
>> + meson_chip->oob_buf,
>> + NFC_OOB_PER_ECC(nand));
>> + }
>>
>> oob_bytes = meson_nfc_get_oob_bytes(nand);
>>
>
>
> Thanks,
> Miquèl

Thanks, Arseniy