[Patch] mpc5200b: improve baud rate calculation (reach high baud rates, better accuracy)

[Grant Likely]

On Tue, Mar 2, 2010 at 1:09 AM, Albrecht Dreß <albrecht.dress at arcor.de> wrote:
>> > +   /* Check only once if we are running on a mpc5200b or not */
>> > +   if (is_mpc5200b == -1) {
>> > +           struct device_node *np;
>> > +
>> > +           np = of_find_compatible_node(NULL, NULL, "fsl,mpc5200b-immr");
>>
>> This should be handled using a new compatible-entry
>> "fsl,mpc5200b-psc-uart".
>
> I agree that this would be a lot cleaner, but it's also a lot more intrusive.  CC'ing the device tree discussion list here... comments, please!!

fsl,mpc5200b-psc-uart is already in the compatible list for all
MPC500b boards currently in the kernel tree.

>> > +           if (np) {
>> > +                   is_mpc5200b = 1;
>> > +                   dev_dbg(&op->dev, "mpc5200b: using /4 prescaler\n");
>>
>> Does this message respect the fallback case?
>
> See comment above...
>
>> You could also have a set_divisor-function for 5200 and 5200B and set it
>> here
>> in the function struct (one reason less for the static ;))
>
> Hmmm, but then I would need a 'static struct psc_ops mpc5200b_psc_ops', where only two functions differ from the generic 52xx struct as it is implemented now.  Using the static int needs less space.  However, in combination with the new compatible entry, it would of course make sense.
>
> Again, any insight from the device tree gurus would be appreciated!

Wolfram is correct, you should set the correct divisor function in the
ops structure.  Much clearer code that way.

g.