linux-kernel - Re: [PATCH v2] mtd: spi-nor: Fix address width on flash chips

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Message-ID: <fa017eb8-2927-8560-7744-65592eb5a391@microchip.com>
Date:   Tue, 6 Oct 2020 11:44:23 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <bert@...t.com>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mtd: spi-nor: Fix address width on flash chips > 16MB

On 10/5/20 12:32 AM, Bert Vermeulen wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> If a flash chip has more than 16MB capacity but its BFPT reports
> BFPT_DWORD1_ADDRESS_BYTES_3_OR_4, the spi-nor framework defaults to 3.
> 
> The check in spi_nor_set_addr_width() doesn't catch it because addr_width
> did get set. This fixes that check.
> 
the problem was uncovered with commit f9acd7fa80be, so maybe a Fixes tag
will help.

Fixes: f9acd7fa80be ("mtd: spi-nor: sfdp: default to addr_width of 3 for configurable widths")
> Signed-off-by: Bert Vermeulen <bert@...t.com>

We can have this automatically in the stable tree by adding the tag:

Cc: stable@...r.kernel.org

Reviewed-by: Tudor Ambarus <tudor.ambarus@...rochip.com>

> ---
>  drivers/mtd/spi-nor/core.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 0369d98b2d12..a2c35ad9645c 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -3009,13 +3009,15 @@ static int spi_nor_set_addr_width(struct spi_nor *nor)
>                 /* already configured from SFDP */
>         } else if (nor->info->addr_width) {
>                 nor->addr_width = nor->info->addr_width;
> -       } else if (nor->mtd.size > 0x1000000) {
> -               /* enable 4-byte addressing if the device exceeds 16MiB */
> -               nor->addr_width = 4;
>         } else {
>                 nor->addr_width = 3;
>         }
> 
> +       if (nor->addr_width == 3 && nor->mtd.size > 0x1000000) {
> +               /* enable 4-byte addressing if the device exceeds 16MiB */
> +               nor->addr_width = 4;
> +       }
> +
>         if (nor->addr_width > SPI_NOR_MAX_ADDR_WIDTH) {
>                 dev_dbg(nor->dev, "address width is too large: %u\n",
>                         nor->addr_width);
> --
> 2.17.1
>