Re: [PATCH 1/2] mtd: spi-nor: Make SFDP-based 4B_OPCODE support detection works correctly

[Cyrille Pitchen - M19942 <cyrille.pitchen@xxxxxxxxxxxxx>]

Hi Boris,

looks good, just a small remark below:

Le 17/10/2018 à 16:44, Boris Brezillon a écrit :
> Some flash_info entries have the SPI_NOR_4B_OPCODES to let the core
> know that the flash supports 4B opcode. While this solution works fine
> for id-based caps detection, it doesn't work that well when relying on
> SFDP-based caps detection. Let's add an SNOR_F_4B_OPCODES flag so that
> spi_nor_parse_bfpt() can add it when the BFPT_DWORD1_ADDRESS_BYTES
> field is set to BFPT_DWORD1_ADDRESS_BYTES_4_ONLY.
> 
> Reported-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 11 ++++++++---
>  include/linux/mtd/spi-nor.h   |  1 +
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 9407ca5f9443..85e57e9ea1b5 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -2643,6 +2643,7 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
>  		break;
>  
>  	case BFPT_DWORD1_ADDRESS_BYTES_4_ONLY:
> +		nor->flags |= SNOR_F_4B_OPCODES;

if spi_nor_parse_sdfp() fails, there is a kind of roll-back operation done
in spi_nor_init_params() to set the struct spi_nor *nor back to its previous
state.

		if (spi_nor_parse_sfdp(nor, &sfdp_params)) {
			nor->addr_width = 0;
			nor->mtd.erasesize = 0;
		} else {
			[...]

maybe "nor->flags &= ~SNOR_F_4B_OPCODES;" should be added there.
If this roll-back block grows too much, maybe we could introduce a
void spi_nor_roll_back_sfdp(struct spi_nor *nor) function.
Also it would make the roll back operation more explicit.

Best regards,

Cyrille

>  		nor->addr_width = 4;
>  		break;
>  
> @@ -3552,7 +3553,7 @@ static int spi_nor_init(struct spi_nor *nor)
>  
>  	if ((nor->addr_width == 4) &&
>  	    (JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) &&
> -	    !(nor->info->flags & SPI_NOR_4B_OPCODES)) {
> +	    !(nor->flags & SNOR_F_4B_OPCODES)) {
>  		/*
>  		 * If the RESET# pin isn't hooked up properly, or the system
>  		 * otherwise doesn't perform a reset command in the boot
> @@ -3586,7 +3587,7 @@ void spi_nor_restore(struct spi_nor *nor)
>  	/* restore the addressing mode */
>  	if ((nor->addr_width == 4) &&
>  	    (JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) &&
> -	    !(nor->info->flags & SPI_NOR_4B_OPCODES) &&
> +	    !(nor->flags & SNOR_F_4B_OPCODES) &&
>  	    (nor->flags & SNOR_F_BROKEN_RESET))
>  		set_4byte(nor, nor->info, 0);
>  }
> @@ -3744,11 +3745,15 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>  		nor->addr_width = 4;
>  		if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
>  		    info->flags & SPI_NOR_4B_OPCODES)
> -			spi_nor_set_4byte_opcodes(nor, info);
> +			nor->flags |= SNOR_F_4B_OPCODES;
>  	} else {
>  		nor->addr_width = 3;
>  	}
>  
> +	if (info->addr_width == 4 &&
> +	    nor->flags & SNOR_F_4B_OPCODES)
> +		spi_nor_set_4byte_opcodes(nor, info);
> +
>  	if (nor->addr_width > SPI_NOR_MAX_ADDR_WIDTH) {
>  		dev_err(dev, "address width is too large: %u\n",
>  			nor->addr_width);
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index 7f0c7303575e..4ffb165f4f85 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -236,6 +236,7 @@ enum spi_nor_option_flags {
>  	SNOR_F_READY_XSR_RDY	= BIT(4),
>  	SNOR_F_USE_CLSR		= BIT(5),
>  	SNOR_F_BROKEN_RESET	= BIT(6),
> +	SNOR_F_4B_OPCODES	= BIT(7)
>  };
>  
>  /**
> 

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