Re: [PATCH v5 01/11] mtd: add datasheet's ECC information tonand_chip{}

From: Artem Bityutskiy
Date: Thu May 16 2013 - 03:11:50 EST

On Thu, 2013-05-16 at 10:16 +0800, Huang Shijie wrote:
> ä 2013å05æ15æ 20:11, Artem Bityutskiy åé:
> > On Wed, 2013-05-15 at 16:40 +0800, Huang Shijie wrote:
> >> + * @ecc_strength: [INTERN] ECC correctability from the datasheet.
> >> + * Minimum amount of bit errors per @ecc_step guaranteed to
> >> + * be correctable. If unknown, set to zero.
> >> + * @ecc_step: [INTERN] ECC step required by the @ecc_strength,
> >> + * also from the datasheet. It is the recommended ECC step
> >> + * size, if known; if unknown, set to zero.
> > Here and in other places you talk about "datasheet". Do you assume that
> > the real ECC strength/step used by NAND chips may be different? Or you
> > assume it must be the same?
> >
> The two fields are used to store the ecc info from the datasheet.
> The two fields are just for a reference.
> [1] The nand controller may do not use these two fields, it's ok;
> For example, the datasheet requires "4bits per 512 bytes".
> The nand controller can uses 8bits per 512 bytes.
> [2] but sometimes the nand controller must use these two fields.
> For example, the datasheet requires "40bits per 1024 bytes".
> For the hardware limit, the nand controller(BCH) may supports the
> 40bits ecc in the maximum.
> So the nand controller must use these two fields now.

I wonder if it makes sense to name things so that it is clear form the
names whether that is the "theoretical" datasheet values or the real
ones. I would prefer to clearly distinguish between them, in names and
comments. Thoughts?

Best Regards,
Artem Bityutskiy

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