linux-kernel - Re: [PATCH v2] mtd: nand: spi: rework detect procedure for different read id op

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Date:   Fri, 10 Jan 2020 15:34:28 +0800
From:   Chuanhong Guo <gch981213@...il.com>
To:     Boris Brezillon <boris.brezillon@...labora.com>
Cc:     linux-mtd@...ts.infradead.org,
        Boris Brezillon <bbrezillon@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mtd: nand: spi: rework detect procedure for different
 read id op

Hi!

On Fri, Jan 10, 2020 at 2:59 PM Boris Brezillon
<boris.brezillon@...labora.com> wrote:
> [...]
> > +     ret = spinand_read_id_op(spinand, 1, 0, id);
> > +     if (ret)
> > +             return ret;
> > +     ret = spinand_manufacturer_match(spinand,
> > +                                      SPINAND_READID_METHOD_OPCODE_ADDR);
> > +     if (!ret)
> > +             return 0;
> > +
> > +     ret = spinand_read_id_op(spinand, 0, 1, id);
>
> Hm, we should probably do only one of each read_id and iterate over all
> manufacturers/chips each time instead of doing 3 read_ids per
> manufacturer.

This actually do the former instead of the latter. Maybe the function
names are a bit
misleading. spinand_manufacturer_match iterates over all manufacturers
in one call,
and spinand_manufacturer_detect is called once in spinand_detect.
Do you have suggestions on function naming?

> [...]
> > + *       SPINAND_READID_METHOD_OPCODE_DUMMY: chip id is returned after
> > + *       read_id opcode + 1 dummy byte.
> > + */
> > +struct spinand_devid {
> > +     u16 id;
>
> Can we make that field an array of u8?
>
>         const u8 *id;
>
> > +     u8 len;
> > +     enum spinand_readid_method method;
> > +};
> [...]
> >
> > +#define SPINAND_ID(__id, __len, __method)                            \
> > +     {                                                               \
> > +             .id = __id,                                             \
> > +             .len = __len,                                           \
> > +             .method = __method,                                     \
> > +     }
>
> That one can be turned into
>
> #define SPINAND_ID(__method, ...)                               \
>         {                                                       \
>                 .id = (const u8[]){ __VA_ARGS },                \
>                 .len = sizeof((u8[]){ __VA_ARGS }),             \
>                 .method = __method,                             \
>         }

Wow. I never thought of this cool trick. I'll give it a try.

Regards,
Chuanhong Guo