Re: [PATCH v3 3/3] mtd: s3c2410: parse the device configuration from OF node

From: Boris Brezillon
Date: Mon Oct 24 2016 - 14:52:11 EST


On Mon, 24 Oct 2016 16:47:38 -0200
Sergio Prado <sergio.prado@xxxxxxxxxxxxxx> wrote:

> On Mon, Oct 24, 2016 at 03:02:01PM +0200, Boris Brezillon wrote:
> > > +static int s3c2410_nand_setup_data_interface(struct mtd_info *mtd,
> > > + const struct nand_data_interface *conf,
> > > + bool check_only)
> > > +{
> > > + struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd);
> > > + struct s3c2410_platform_nand *pdata = info->platform;
> > > + const struct nand_sdr_timings *timings;
> > > + int tacls;
> > > +
> > > + timings = nand_get_sdr_timings(conf);
> > > + if (IS_ERR(timings))
> > > + return -ENOTSUPP;
> > > +
> > > + tacls = timings->tCLS_min - timings->tWP_min;
> > > + if (tacls < 0)
> > > + tacls = 0;
> > > +
> > > + pdata->tacls = DIV_ROUND_UP(tacls, 1000);
> > > + pdata->twrph0 = DIV_ROUND_UP(timings->tWP_min, 1000);
> > > + pdata->twrph1 = DIV_ROUND_UP(timings->tCLH_min, 1000);
> >
> > You seem to only apply the timings in s3c2410_nand_setrate(), which is
> > only called at probe time or on a cpufreq even, but the core can change
> > timings at runtime (this is what happens each time you reset the chip).
> >
> > To support that you have 2 options:
> > - apply the timings in ->select_chip()
> > - apply the timings here
>
> Right. As far as I understood, ->setup_data_interface() will be called
> when MTD core change timings at runtime, so it is enough to apply the
> timings in the end of ->setup_data_interface()?

If your controller does not support interfacing with multiple chips,
then yes, it should work.