linux-kernel - Re: [PATCH v3] mtd: spi-nor: fix nor->addr_width when its value configured from SFDP does not match the actual width

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Message-ID: <5ffc9e32-ff69-9819-7bfd-ad9f793bb629@microchip.com>
Date:   Sat, 22 Jun 2019 11:49:25 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <liu.xiang6@....com.cn>, <linux-mtd@...ts.infradead.org>
CC:     <bbrezillon@...nel.org>, <richard@....at>,
        <linux-kernel@...r.kernel.org>, <marek.vasut@...il.com>,
        <liuxiang_1999@....com>, <computersforpeace@...il.com>,
        <dwmw2@...radead.org>, <nagasure@...inx.com>, <vigneshr@...com>
Subject: Re: [PATCH v3] mtd: spi-nor: fix nor->addr_width when its value
 configured from SFDP does not match the actual width

Hi, Liu,

On 03/31/2019 10:42 AM, Liu Xiang wrote:

> Some is25lp256 get BFPT_DWORD1_ADDRESS_BYTES_3_ONLY from BFPT table for
> address width. But in actual fact the flash can support 4-byte address.
> So we should fix it.

It's better to be imperative. Substitute "So we should fix it" with something
like "Use a post bfpt fixup hook to overwrite the address width advertised by
the BFPT".

>

We'll need a fixes tag here.> Suggested-by: Boris Brezillon <bbrezillon@...nel.org>
> Suggested-by: Vignesh Raghavendra <vigneshr@...com>

When? If they didn't explicitly suggested this approach, lets drop the S-b tags.

> Signed-off-by: Liu Xiang <liu.xiang6@....com.cn>
> ---
> 
> Changes in v3:
>  add a fixup for is25lp256 to solve the address width problem.
> 
>  drivers/mtd/spi-nor/spi-nor.c | 25 ++++++++++++++++++++++++-
>  1 file changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 6e13bbd..d252a66 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -1682,6 +1682,28 @@ static int sr2_bit7_quad_enable(struct spi_nor *nor)
>  		.flags = SPI_NOR_NO_FR | SPI_S3AN,
>  
>  static int
> +is25lp256_post_bfpt_fixups(struct spi_nor *nor,
> +			   const struct sfdp_parameter_header *bfpt_header,
> +			   const struct sfdp_bfpt *bfpt,
> +			   struct spi_nor_flash_parameter *params)
> +{
> +	/*
> +	 * IS25LP256 supports 4B opcodes.
> +	 * Unfortunately, some devices get BFPT_DWORD1_ADDRESS_BYTES_3_ONLY
                            ^ which devices, did you get a list from issi?

> +	 * from BFPT table for address width. We should fix it.

How about "IS25LP256 supports 4B opcodes, but the BFPT advertises a
BFPT_DWORD1_ADDRESS_BYTES_3_ONLY address width. Overwrite the address width
advertised by the BFPT."

> +	 */
> +	if ((bfpt->dwords[BFPT_DWORD(1)] & BFPT_DWORD1_ADDRESS_BYTES_MASK) ==
> +		BFPT_DWORD1_ADDRESS_BYTES_3_ONLY)
> +		nor->addr_width = 4;
> +
> +	return 0;
> +}
> +
> +static struct spi_nor_fixups is25lp256_fixups = {

Naga will use "is25lp256_fixups" for the is25wp256 too, but it's not the case to
change the name yet. All good here.

I really want to have this in next, can I have an update in the next few days?

Cheers,
ta