[U-Boot-Users] [RFC] Remove some redundant fdt code from do_bootm_linux

[Jerry Van Baren]

Andy Fleming wrote:
> There were a number of places where libfdt and the old ft code
> were doing essentially the same thing.  By adding some stubs for
> some of the libfdt convenience functions, we can eliminate some
> of these redundancies.
> 
> This patch has some overlap with a patch Jerry already submitted, so I'm 
> not expecting this to apply.  I'm just interested in opinions as to 
> whether this is a good approach.
> 
> In the process:
> * Eliminated a bug in the libfdt error handling for uImages where
>   a correct header would trigger an error

Did my latest patch set fix this or am I still missing it?

> * Moved the debug message about transferring control to Linux
>   next to the first potential invocation of Linux

Yup, that's all changed now, hopefully for the better...  If I missed 
something or if something could be improved, hollar.

> * Did a few minor formatting tweaks to improve readability
> * Removed what appeared to be redundant calls to fdt_chosen,
>   fdt_env, and fdt_bd_t

Hmm, that sure looks redundant.  What was I thinking???  Oh yeah, that's 
right, I wasn't thinking when I hacked up bootm.  :-(

> * Eliminated the #ifdef protecting the if statement which checked
>   if we had an of_flat_tree.  If CONFIG_OF_FLAT_TREE or
>   CONFIG_OF_LIBFDT aren't defined, then of_flat_tree will be NULL
>   (and any compiler will eliminate the check in that case)

Makes sense.  Simplifying is GOOD.  We may want to keep the #ifdef 
around "of_data" to prevent a "unused variable" compiler warning (or 
maybe it isn't a problem, I didn't really look at it).

> * Made clear in a few places that LIBFDT and OF_FLAT_TREE are
>   mutually exclusive
> * Added definition for fdt_check_header (evaluates to 0 if the
>   header is of type OF_DT_HEADER
> * Added definition for fdt_totalsize() (evaluates to the value of totalsize)
> * Added a stub for fdt_open_into() which just does the memmove and returns 0

WRT the above, my intent is to evangelize for LIBFDT, convert the other 
targets that use fdt to LIBFDT, and remove OF_FLAT_TREE.  That solves 
the above bullets in a whole lot cleaner fashion.  LIBFDT does 
everything OF_FLAT_TREE does and much more.  It's just a problem of time 
(unlike Wolfgang, I need to sleep ;-).

The conversion is not difficult, following my lead on the MPC8360. 
There are three functions that need to be updated.  The three functions 
that need to be converted are:
* ft_board_setup
* ft_cpu_setup
* ft_pci_setup

See the table in the ToDo section:
   <http://www.denx.de/wiki/view/UBoot/UBootFdtInfo#ToDo>

> Signed-off-by: Andy Fleming <afleming at freescale.com>

Thanks for the thoughts & proposals,
gvb