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

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Fri, 19 Oct 2018 09:50:31 +0200
Cyrille Pitchen - M19942 <cyrille.pitchen@microchip.com> wrote:

> 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@bootlin.com>
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > ---
> >  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;

Looks like the ->addr_width=0; as been lost when adding support for
non-uniform erase size.

> 			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)
> >  };
> >  
> >  /**
> >