Re: [PATCH v3 1/9] mtd: nand: define struct nand_timings

Brian Norris
2014-05-20T18:13:12Z

On Thu, May 08, 2014 at 03:29:30PM +0100, Lee Jones wrote:
> >
> > Please document the units for these fields here. It looks like you're
> > using picoseconds.
>
> Can't we leave this open to interpretation? For instance, it's more
> convenient for our driver to handle these as nano second values.

No, their values will be determined by the nand_base core, and we must
have something consistent for drivers to rely on. However, I don't
really have a hard preference on nanoseconds versus picoseconds. If we
see that many of the values reach low-digit nanosecons, or fractional
nanoseconds, it probably makes sense to have the higher resolution.

> > > +struct nand_sdr_timings {
...
> > > + u32 tCS_min;
>
> u32 tCSD_min;

Is this a suggested addition, Lee? I agree with Boris that this looks
like a DDR mode, which should not be covered here.

> > > + u32 tDH_min;
> > > + u32 tDS_min;
> > > + u32 tFEAT_max;
> > > + u32 tIR_min;
> > > + u32 tITC_max;
>
> u32 tR_max;

Same here, is this a suggested new field? If you need it, then we can
follow up like Boris suggested, with a different method, since tR is not
part of the electrical parameters of the timing mode.

...
> > > +};
> > > +
> > > #endif /* __LINUX_MTD_NAND_H */

Brian