linux-kernel - Re: [PATCH] mtd: spi-nor: winbond: add Zetta ZD25Q128C support

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Message-ID: <mafs0v805zwlv.fsf@kernel.org>
Date: Mon, 12 Aug 2024 15:42:04 +0200
From: Pratyush Yadav <pratyush@...nel.org>
To: Michael Walle <mwalle@...nel.org>
Cc: Tudor Ambarus <tudor.ambarus@...aro.org>,  Pratyush Yadav
 <pratyush@...nel.org>,  Miquel Raynal <miquel.raynal@...tlin.com>,
  Richard Weinberger <richard@....at>,  Vignesh Raghavendra
 <vigneshr@...com>,  linux-mtd@...ts.infradead.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: spi-nor: winbond: add Zetta ZD25Q128C support

On Mon, Aug 05 2024, Michael Walle wrote:

> Zetta normally uses BAh as its vendor ID. But for the ZD25Q128C they
> took the one from Winbond and messed up the size parameters in SFDP.
> Most functions seem compatible with the W25Q128, we just have to fix up
> the size.
>
> Link: http://www.zettadevice.com/upload/file/20150821/DS_Zetta_25Q128_RevA.pdf
> Link: https://www.lcsc.com/datasheet/lcsc_datasheet_2312081757_Zetta-ZD25Q128CSIGT_C19626875.pdf
> Signed-off-by: Michael Walle <mwalle@...nel.org>
> ---
[...]
> diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
> index e065e4fd42a3..9f7ce5763e71 100644
> --- a/drivers/mtd/spi-nor/winbond.c
> +++ b/drivers/mtd/spi-nor/winbond.c
> @@ -17,6 +17,31 @@
>  		   SPI_MEM_OP_NO_DUMMY,					\
>  		   SPI_MEM_OP_DATA_OUT(1, buf, 0))
>  
> +static int
> +w25q128_post_bfpt_fixups(struct spi_nor *nor,
> +			 const struct sfdp_parameter_header *bfpt_header,
> +			 const struct sfdp_bfpt *bfpt)
> +{
> +	/*
> +	 * Zetta ZD25Q128C is a clone of the Winbond device. But the encoded
> +	 * size is really wrong. It seems that they confused Mbit with MiB.
> +	 * Thus the flash is discovered as a 2MiB device.
> +	 */
> +	if (bfpt_header->major == SFDP_JESD216_MAJOR &&
> +	    bfpt_header->minor == SFDP_JESD216_MINOR &&
> +	    nor->params->size == SZ_2M &&
> +	    nor->params->erase_map.regions[0].size == SZ_2M) {
> +		nor->params->size = SZ_16M;
> +		nor->params->erase_map.regions[0].size = SZ_16M;
> +	}

Since the size is 16 MiB for both Zetta and Winbond, why do you have
these conditions here? Why not just do it unconditionally? What
situation do you want to protect against?

> +
> +	return 0;
> +}
> +
> +static const struct spi_nor_fixups w25q128_fixups = {
> +	.post_bfpt = w25q128_post_bfpt_fixups,
> +};
> +
>  static int
>  w25q256_post_bfpt_fixups(struct spi_nor *nor,
>  			 const struct sfdp_parameter_header *bfpt_header,
> @@ -108,6 +133,7 @@ static const struct flash_info winbond_nor_parts[] = {
>  		.size = SZ_16M,
>  		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB,
>  		.no_sfdp_flags = SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ,
> +		.fixups = &w25q128_fixups,
>  	}, {
>  		.id = SNOR_ID(0xef, 0x40, 0x19),
>  		.name = "w25q256",

-- 
Regards,
Pratyush Yadav