[U-Boot-Users] Re: Patch: Support for PQ27e (8247/48/71/72) chips and MPC8272ADS board

Yuli Barcohen
2004-03-17T11:46:33Z

>>>>> Wolfgang Denk writes:

Yuli> This would require that, for every PQ27e-based board, it would
Yuli> be defined in the board configuration file that it's PQ27e and
Yuli> not just
Yuli> 8260. Then CPM_DATAONLY_SIZE can be defined conditionally on
Yuli> this definition in cpm_8260.h. I personally don't like such
Yuli> compile-time definitions because chip version can be easily
Yuli> detected in run-time.

Wolfgang> The advantage of compile-time definitions is that they
Wolfgang> result in smaller code.

Of course, but here we're speaking about couple of `if's.

Wolfgang> PQ27E_FCC_SPECIAL_BASE vs. CPM_FCC_SPECIAL_BASE ...

Yuli> Well, the question is if it's better that the CPU-specific
Yuli> code will silently handle the differences or we'll make it the
Yuli> user's responsibility to define the difference manually. I
Yuli> think automatic handling is better but if you insist on
Yuli> #ifdefs, I can implement it too.

Wolfgang> Sorry, but I can't follow.

Wolfgang> From what I have seen your patches used _two_ #defines
Wolfgang> instead of one.

Well, my explanations can be confusing... I'll try to explain it
differently. You're right, there are two #defines in one common file and
it's all what needed for PQ27e support. If you prefer the compile-time
solution, this means that: new CPU type is to be defined (CONFIG_MPC8272
or something like this) in addition to CONFIG_MPC8260, this type must be
used for every PQ27e based board instead of CONFIG_MPC8260, and in a
common file it must be defined that CONFIG_MPC8272 is a flavour of
CONFIG_MPC8260 otherwise the common MPC8260 code won't work for
PQ27e. IMHO this means much more work and more possibilities to make a
mistake, especially when porting U-Boot to a new board, but you're the
maintainer so make your choice.

--
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Yuli Barcohen | Phone +972-9-765-1788 | Software Project Leader
yuli at arabellasw.com | Fax +972-9-765-7494 | Arabella Software, Israel
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