linux-kernel - Re: [PATCH v2] mtd: rawnand: meson: fix bitmask for length in command word

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Date:   Wed, 29 Mar 2023 09:09:20 +0100
From:   Tudor Ambarus <tudor.ambarus@...aro.org>
To:     Arseniy Krasnov <avkrasnov@...rdevices.ru>,
        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>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        Yixun Lan <yixun.lan@...ogic.com>
Cc:     linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...rdevices.ru, oxffffaa@...il.com
Subject: Re: [PATCH v2] mtd: rawnand: meson: fix bitmask for length in command
 word



On 3/29/23 08:47, Arseniy Krasnov wrote:
> Valid mask is 0x3FFF, without this patch the following problems were
> found:
> 
> 1) [    0.938914] Could not find a valid ONFI parameter page, trying
>                   bit-wise majority to recover it
>    [    0.947384] ONFI parameter recovery failed, aborting
> 
> 2) Read with disabled ECC mode was broken.
> 
> Fixes: 8fae856c5350 ("mtd: rawnand: meson: add support for Amlogic NAND flash controller")
> Cc: <Stable@...r.kernel.org>
> Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
> ---
>  drivers/mtd/nand/raw/meson_nand.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index a28574c00900..074e14225c06 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -280,7 +280,7 @@ static void meson_nfc_cmd_access(struct nand_chip *nand, int raw, bool dir,
>  
>  	if (raw) {
>  		len = mtd->writesize + mtd->oobsize;
> -		cmd = (len & GENMASK(5, 0)) | scrambler | DMA_DIR(dir);
> +		cmd = (len & GENMASK(13, 0)) | scrambler | DMA_DIR(dir);

What happens when len > GENMASK(13, 0)? Do you check this somewhere?

Please introduce a macro/field for GENMASK(13, 0), having such mask
scattered along the code looks hackish and doesn't help readability.
You'll get to use FIELD_PREP as well.

>  		writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  		return;
>  	}
> @@ -544,7 +544,7 @@ static int meson_nfc_read_buf(struct nand_chip *nand, u8 *buf, int len)
>  	if (ret)
>  		goto out;
>  
> -	cmd = NFC_CMD_N2M | (len & GENMASK(5, 0));
> +	cmd = NFC_CMD_N2M | (len & GENMASK(13, 0));
>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  
>  	meson_nfc_drain_cmd(nfc);
> @@ -568,7 +568,7 @@ static int meson_nfc_write_buf(struct nand_chip *nand, u8 *buf, int len)
>  	if (ret)
>  		return ret;
>  
> -	cmd = NFC_CMD_M2N | (len & GENMASK(5, 0));
> +	cmd = NFC_CMD_M2N | (len & GENMASK(13, 0));
>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  
>  	meson_nfc_drain_cmd(nfc);