[U-Boot] [RFC] New init sequence processing without init_sequence array

[Wolfgang Denk]

Dear Graeme Russ,

In message <1313587343-3693-1-git-send-email-graeme.russ at gmail.com> you wrote:
> I have been thinking about the problem of the pesky init_sequence arrays
> and the inevitable #ifdefs and empty stub functions that result so I
> thought I'de have a crack at a more dynamic implementation. And like all
> good programmers, I stole the solution ;). This implementation is based
> on Linux's __initcall(fn) et. al. macros
> 
> If this works cross-platform, we can finally move board_init_* into
> /lib/ - Wouldn't that be nice
> 
> Thoughts?

My initial thoughts are these two:

1. I think we should change the code in a different order.  I would
   prefer to first unify the init code across architectures (the big
   ARM reorganization we just seem to have overcome was an important
   prerequisite for this), before we start changing the init code.

2. One of the advantages of the current implementation is that there
   is a central place in the code (well, at least per architecture,
   untill we unify these as mentioned above) where you can see exactly
   which steps get performed in which sequence.

   I understand (and appreciate) your intentions, does the initcall
   concept not mean that we will have some sort of sequence numbers
   distributed all over the code?  Maybe I'm mising something - but
   does this not make it really difficult to actually see (from the
   source code) what the exact init sequence is?

3. Hardware initialization in inherently very much hardware depen-
   dent ;-)  We have some boards where PCI must be initialized early
   because it is needed to access some other peripherals like memory.
   And we have other boards where PCI can only be initialized late
   because it depends on a lot of other functions that must be working
   first.

   I explained this a number of times before: the current code was
   designed to allow even for completely board specific init
   sequences, by simply adding #define for the list of init functions
   to the board config file - see for example here:

   http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/33951/focus=36436

   http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/72131/focus=72136

   If you look at the current code - heavily larded with #ifdefs of
   all shapes and colors - I cannot see any good way to transform this
   into an initcall (and thus sequence number based) implementation.
   Do you have any specific ideas how to address this?

Best regards,

Wolfgang Denk

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