Re: [PATCH v3 1/2] mtd: spi-nor: Make sure SFDP-based 4B_OPCODE support detection works correctly

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

On Thu, 8 Nov 2018 16:55:29 +0000
<Tudor.Ambarus@microchip.com> wrote:

> On 10/31/2018 04:45 PM, Boris Brezillon wrote:
> > Some flash_info entries have the SPI_NOR_4B_OPCODES flag set 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>
> > Tested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> > ---
> > Changes in v3:
> > - Clear SNOR_F_4B_OPCODES flag when SFDP fails
> > - Add Alexandre R-b
> > 
> > Changes in v2:
> > - Fix the commit message
> > - Fix the ->addr_width check
> > - Add a comma at the end of the SNOR_F_4B_OPCODES definition
> > ---
> >  drivers/mtd/spi-nor/spi-nor.c | 12 +++++++++---
> >  include/linux/mtd/spi-nor.h   |  1 +
> >  2 files changed, 10 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> > index 3e54e31889c7..798915b5c2b0 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;
> >  		nor->addr_width = 4;
> >  		break;
> >  
> > @@ -3252,6 +3253,7 @@ static int spi_nor_init_params(struct spi_nor *nor,
> >  
> >  		if (spi_nor_parse_sfdp(nor, &sfdp_params)) {
> >  			nor->addr_width = 0;
> > +			nor->flags &= ~SNOR_F_4B_OPCODES;
> >  			/* restore previous erase map */
> >  			memcpy(&nor->erase_map, &prev_map,
> >  			       sizeof(nor->erase_map));
> > @@ -3554,7 +3556,7 @@ 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
> > @@ -3588,7 +3590,7 @@ 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);
> >  }
> > @@ -3746,11 +3748,15 @@ 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 (nor->addr_width == 4 &&  
> 
> Shouldn't SNOR_F_4B_OPCODES already imply nor->addr_width == 4?

Can't we have NORs supporting 4B opcodes but are less than 16MB? In
this case SNOR_F_4B_OPCODES would be set and ->addr_width would be 3.

> When SNOR_F_4B_OPCODES comes from bfpt, addr_width is set to 4. For the id-based
> caps detection, when mtd->size > 0x1000000, we set nor->addr_width = 4 too.
> 
> The only uncovered case would be when
>         } else if (info->addr_width) {
>                 nor->addr_width = info->addr_width;
> 
> but this can be solved by reordering the else if cases.
> 
>         if (nor->addr_width) {
>                 /* already configured from SFDP */
>         } else if (mtd->size > 0x1000000) {
> 		...
>         } else if (info->addr_width) {
>                 nor->addr_width = info->addr_width;
>         } else {
>                 nor->addr_width = 3;
>         }
> 
> What do you think?

I'd rather not change that in this patch, but feel free to propose
a patch on top of mine to simplify the logic if you think it's
needed.

> 
> > +	    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..5bc75110d5ea 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),
> >  };
> >  
> >  /**
> >