linux-kernel - Re: [PATCH v2] mtd: spi-nor: macronix: enable 4-bit BP support for MX25L6405D

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Message-ID: <93b7f8e8-cdf4-5b09-da17-636d8fcaf0ee@microchip.com>
Date:   Sat, 23 Jan 2021 12:18:41 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <liew.s.piaw@...il.com>, <michael@...le.cc>
CC:     <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: macronix: enable 4-bit BP support for
 MX25L6405D

Hi, Sieng,

On 12/8/20 3:57 AM, Sieng Piaw Liew wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Enable 4-bit Block Protect support for MX256405D and its variants using
> the same ID.
> 
> Tested on Innacom W3400V6 router with MX25L6406E chip.
> https://github.com/openwrt/openwrt/pull/3501
> 
> Signed-off-by: Sieng Piaw Liew <liew.s.piaw@...il.com>
> ---
> Changes in v2:
> - Add SPI_NOR_HAS_LOCK which SPI_NOR_4BIT_BP required.
> 
>  drivers/mtd/spi-nor/macronix.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/macronix.c b/drivers/mtd/spi-nor/macronix.c
> index 9203abaac229..033ede381673 100644
> --- a/drivers/mtd/spi-nor/macronix.c
> +++ b/drivers/mtd/spi-nor/macronix.c
> @@ -42,7 +42,9 @@ static const struct flash_info macronix_parts[] = {
>         { "mx25l1606e",  INFO(0xc22015, 0, 64 * 1024,  32, SECT_4K) },
>         { "mx25l3205d",  INFO(0xc22016, 0, 64 * 1024,  64, SECT_4K) },
>         { "mx25l3255e",  INFO(0xc29e16, 0, 64 * 1024,  64, SECT_4K) },
> -       { "mx25l6405d",  INFO(0xc22017, 0, 64 * 1024, 128, SECT_4K) },
> +       { "mx25l6405d",  INFO(0xc22017, 0, 64 * 1024, 128,
> +                             SECT_4K | SPI_NOR_HAS_LOCK |
> +                             SPI_NOR_4BIT_BP) },

I've read again the datasheet[1], and to me it looks like we
don't support the locking scheme for this flash.
What mx25l6405d calls BP3, we refer to as Top/Bottom support (TB bit).
The problem that I see is that mx25l6405d uses some kind of twisted
TB bit.

For example, for BP3=1, BP2=0, BP1=0, BP0=1, the flash's datasheet
states that the lower half blocks are protected (0th-63th), while in 
our code we would expect that just the lower first two blocks to be
protected (0th and 1st). We need new support for this flash.

Cheers,
ta

[1] https://www.macronix.com/Lists/Datasheet/Attachments/7309/MX25L6405D,%203V,%2064Mb,%20v1.5.pdf

>         { "mx25u2033e",  INFO(0xc22532, 0, 64 * 1024,   4, SECT_4K) },
>         { "mx25u3235f",  INFO(0xc22536, 0, 64 * 1024,  64,
>                               SECT_4K | SPI_NOR_DUAL_READ |
> --
> 2.17.1
>