Timur Tabi <ti...@freescale.com> wrote on 10/09/2009 15:29:35:
>
> Joakim Tjernlund wrote:
>
> >> A while back, someone posted a version of this code that computed the
> >> values
> >> of fdr/dfsr. I nack'd that patch because I thought the algorithm was too
> >
> > Not so sure about that, but I haven't tried to calc it generally.
>
> A quick way to check this is to figure out which dfsr/fdr values the i2c code
> uses, and then modify that entry in the table with a different pair. You'd
> have to manually calculate the correct value of fdr for the given dfsr.
The code was using 1, most entries has 1 as DFSR so that is no surprise.
I have calculated DFSR and max is 6 for my 8321, CSB=133.332 MHz, board.
Using this value works for me.
>
> > Yes, and a way to #define wanted DFSR. From there one can select
> > one of the 4 tables listed in AN2919. The sum of tabels will be rather big
> > though
> > so I suspect it will less code to calculate the FDR/DFSR.
>
> In this case, you're right. But so far, you're the only person who's
> complained to me that the current code doesn't work, and you already admitted
> that your board is broken, so I don't really see the need to change the code.
Come on, just because my board is somewhat broken, it doesn't mean the
driver is correct. If I define my speed to 100KHz I get
a DFSR of 22, way over what is allowed for my board.
It "works" because nobody has noticed the occasional error and/or doesn't
operate in a noisy env.
Jocke
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