[U-Boot] U-Boot 2012.10 - pxa270 CPU Unknown / no turbo

[Marek Vasut <marex@denx.de>]

Dear Andreas Puls,

> Dear Marek Vasut,
> 
> > Dear Andreas Puls,
> > 
> > > Dear Marek Vasut,
> > > 
> > > > Dear Andreas Puls,
> > > > 
> > > > > Hi together,
> > > > > 
> > > > > i've got another problem with latest stable U-Boot-2012.10 and a
> > > > > Toradex Colibri PXA270 V2.4
> > > > > 
> > > > > Uboot dosen't regonized the CPU Revision
> > > > > u-boot summary screen:
> > > > > 
> > > > > U-Boot 2012.10 (Nov 12 2012 - 14:22:12)
> > > > > CPU: Marvell PXA27x rev. Unknown
> > > > 
> > > > See arch/arm/cpu/pxa/cpuinfo.c , patch is welcome ... they probably
> > > > rolled out
> > > > some new CPU version.
> > > 
> > > Yes, its a PXA270 M. There is a spec. update pdf from Marvel.
> > 
> > http://www.marvell.com/application-processors/pxa-family/assets/pxa_27x_s
> > pe
> > 
> > > c_update.pdf - Table 2-3.
> > > 
> > > They changed the Stepping from A0...C5 to "PXA270M -- A1"
> > > A colleague would support me to change this becouse i have no cloue
> > 
> > about
> > 
> > > writing C Files. So we would like ask you first if the right CPU Name
> > > should be shown in the summary screen which would be a rewrite of your
> > > function or only the right stepping with the old CPU Name would be
> > 
> > enough
> > 
> > > ? (Damn it - hope you understand my Denglish)
> > 
> > Can the CPUs be distinguished in some deterministic way? If so, rewrite
> > it, no
> > problem.
> 
> Both CPU types have the same basic CPU ID, only the 4 stepping bits (the
> 4 LSBs of the CPU ID) are different. So basically the existing functions
> could be extended just to handle the new stepping code.
> 
> However, the naming scheme of the new CPU type according to the data
> sheet is quite different than the older steppings.
> 
> Older PXA270 versions have the following CPU ID, wher the last hex digit
> (the 4 LSBs) is the stepping code, e.g.:
> 
> CPU ID: 0x69054111, stepping code 1 --> PXA270 -- A1
> 
> The Marvell Spec Update Manual shows the new Stepping and CPU ID as
> follows:
> 
> CPU ID: 0x69054118, stepping code 8 --> PXA270M -- A1
> 
> So for stepping code 8 the revision name A1 is the same as for stepping
> code 1, but the CPU base name has changed from PXA270 to PXA270M for the
> new type.
> 
> So just extending the existing stepping decoding function would lead to
> confusion since the existing code would print
> 
>    PXA270 rev. A1
> 
> for bothe the oldest and the newest CPU type, where something like
> 
>    PXA270M rev. A1
> 
> would be correct for stepping code 8. I'm not sure which would be the
> best way to handle this situation and change the code accordingly.

Try something, submit a patch, then we'll discuss it further above some code. 
Let's stop theoreticizing now.

Best regards,
Marek Vasut