[U-Boot] [PATCH 2/2] fsl_i2c: Add CONFIG_FSL_I2C_CUSTOM_DFSR

[Joakim Tjernlund]

Wolfgang Grandegger <wg at denx.de> wrote on 16/09/2009 12:22:05:
>
> Joakim Tjernlund wrote:
> >> Timur Tabi <timur at freescale.com> wrote on 15/09/2009 21:04:47:
> >>> Joakim Tjernlund wrote:
> >>>
> >>>> No, the impact on speed from DFSR is pretty small so it will
> >>>> be close enough.
> >>> How small?
> >> From the app note:
> >>   divisor = B * (A + ((3*C)/B)*2);
> >>
> >> C is dfsr and 10 <= A <= 30, 16 <= B <= 2048
> >> Considering the actual speed may be way lower the requested speed
> >> I think this is small enough.
> >
> > Once we have the new procedure in place, we can calculate the exact
> > divisor so the need for extra CONFIG_ options goes away.
>
> As Timur pointed out, a new table/algorithm would require some real
> testing and also some feedback from the users. Who knows if "your"
> values do not make trouble. Therefore I vote for using custom
> settings for maximum flexibility:
>
>   CONFIG_FSL_I2C_CUSTOM_FDR
>   CONFIG_FSL_I2C_CUSTOM_DFSR

Oh well, since you both wanted it I added it.
Sent 3 patches, the last patch impl. the latest AN2819 spec.

Would you mind test it a little?

      Jocke