linux-kernel - Re: [PATCH v1] mtd: rawnand: meson: handle OOB buffer according OOB layout

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Date:   Thu, 09 Nov 2023 11:06:58 +0300
From:   Viacheslav Bocharov <adeep@...ina.in>
To:     Arseniy Krasnov <avkrasnov@...utedevices.com>,
        Liang Yang <liang.yang@...ogic.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     oxffffaa@...il.com, kernel@...rdevices.ru,
        linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mtd: rawnand: meson: handle OOB buffer according OOB
 layout

Hi!

On Thu, 2023-11-09 at 08:39 +0300, Arseniy Krasnov wrote:
> In case of MTD_OPS_AUTO_OOB mode, MTD/NAND layer fills/reads OOB buffer
> according current OOB layout so we need to follow it in the driver.
> 
> Signed-off-by: Arseniy Krasnov <avkrasnov@...utedevices.com>
> ---
>  drivers/mtd/nand/raw/meson_nand.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index 561d46d860b7..0d4d358152d7 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -510,7 +510,7 @@ static void meson_nfc_set_user_byte(struct nand_chip *nand, u8 *oob_buf)
>  	__le64 *info;
>  	int i, count;
>  
> -	for (i = 0, count = 0; i < nand->ecc.steps; i++, count += 2) {
> +	for (i = 0, count = 0; i < nand->ecc.steps; i++, count += (2 + nand->ecc.bytes)) {
>  		info = &meson_chip->info_buf[i];
>  		*info |= oob_buf[count];
>  		*info |= oob_buf[count + 1] << 8;
Seems something wrong with your logic here.
I think this code should most likely look like this:

for (i = 0, count = 0; i < nand->ecc.steps; i++, count += nand->ecc.bytes) {
    info = &meson_chip->info_buf[i];
    *info |= oob_buf[count];
    if (nand->ecc.bytes > 1)
      *info |= oob_buf[count + 1] << 8;
}


> @@ -523,7 +523,7 @@ static void meson_nfc_get_user_byte(struct nand_chip *nand, u8 *oob_buf)
>  	__le64 *info;
>  	int i, count;
>  
> -	for (i = 0, count = 0; i < nand->ecc.steps; i++, count += 2) {
> +	for (i = 0, count = 0; i < nand->ecc.steps; i++, count += (2 + nand->ecc.bytes)) {
>  		info = &meson_chip->info_buf[i];
>  		oob_buf[count] = *info;
>  		oob_buf[count + 1] = *info >> 8;
And there:

for (i = 0, count = 0; i < nand->ecc.steps; i++, count += nand->ecc.bytes) {
    info = &meson_chip->info_buf[i];
    oob_buf[count] = *info;
    if (nand->ecc.bytes > 1)
        oob_buf[count + 1] = *info >> 8;
}


This is more similar to the behavior of similar functions in the proprietary U-Boot.

--
Viacheslav Bocharov