[PATCH v3 2/5] mtd: spi-nor: core: Hook manufacture by checking first byte ID

[liao jaime]

Hi Michael

>
> Am 2023-08-04 11:54, schrieb Jaime Liao:
> > From: JaimeLiao <jaimeliao at mxic.com.tw>
> >
> > Patch ID for flash support is a thing that we keep striving to do.
> > Follow the optimization of software architecture, parse SFDP is
> > the mainstream in SPI-NOR subsystem.
> > Label "spi-nor-generic" to the flash which didn't include in ID table
> > but support SFDP, is a good way for flash support.
> > Building upon this fundation, achieve hooking the manufacturer using
> > the
> > 1st ID byte.
>
> This won't work beacuse the manufacturer id is not always
> one byte long, think of continuation codes. In fact, as the
> flash_info table is of now, we cannot even rely on the
> continuation codes, but we have to always check for the
> complete id_len, i.e. there is at least one hack where
> the id is reversed and the manufacturer is the last byte,
> iirc. some oddball cypress mram chip.
According JEDEC standard, 1st byte is manufacture ID.
I check id table, "cy15x104q" with multi manufacture ID in
later bytes by RDID command(9F).
Maybe some old flash didn't follow this but I think it isn't
a high percentage.
Most of all and new product are follow JEDEC.

>
> If you want to get the correct manufacturer for spi-nor-generic,
> you should extract it from the SFDP tables. It seems that the
> BFPT don't include a manufacturer id, but if there are proprietary
> tables, you *might* use that id. I say might, because it only works
> with one byte manufacturer ids, no continuation codes... *sigh*
Unfortunately, Macronix didn't include proprietary tables in SFDP for
octal flashes and as I understanding proprietary table is not a stardard.
So that content and address are not identical each vendor, it will need
a manufacturer fixups for reading.

>
> -michael
>
>
> > Consequently, extend support even for parts not descibed in SFDP.
> >
> > Signed-off-by: JaimeLiao <jaimeliao at mxic.com.tw>
> > ---
> >  drivers/mtd/spi-nor/core.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> > index 5f29fac8669a..eb0a09c06bf4 100644
> > --- a/drivers/mtd/spi-nor/core.c
> > +++ b/drivers/mtd/spi-nor/core.c
> > @@ -2036,10 +2036,13 @@ static const struct flash_info
> > *spi_nor_match_id(struct spi_nor *nor,
> >       for (i = 0; i < ARRAY_SIZE(manufacturers); i++) {
> >               for (j = 0; j < manufacturers[i]->nparts; j++) {
> >                       part = &manufacturers[i]->parts[j];
> > -                     if (part->id_len &&
> > -                         !memcmp(part->id, id, part->id_len)) {
> > -                             nor->manufacturer = manufacturers[i];
> > -                             return part;
> > +                     if (part->id_len) {
> > +                             /* Hook manufacturers when first byte (maf ID) is same as other
> > IDs on ID table */
> > +                             if (!nor->manufacturer && !memcmp(part->id, id, 1))
> > +                                     nor->manufacturer = manufacturers[i];
> > +
> > +                             if (!memcmp(part->id, id, part->id_len))
> > +                                     return part;
> >                       }
> >               }
> >       }

Thanks
Jaime