[U-Boot] [PATCH] dm: core: Enable optional use of fdt_translate_address()

[Stefan Roese <sr@denx.de>]

Hi Simon,

On 09.09.2015 20:07, Simon Glass wrote:
> On Thursday, 3 September 2015, Stefan Roese <sr@denx.de> wrote:
>>
>> The current "simple" address translation simple_bus_translate() is not
>> working on some platforms (e.g. MVEBU). As here more complex "ranges"
>> properties are used in many nodes (multiple tuples etc). This patch
>> enables the optional use of the common fdt_translate_address() function
>> which handles this translation correctly.
>>
>> Signed-off-by: Stefan Roese <sr@denx.de>
>> Cc: Simon Glass <sjg@chromium.org>
>> Cc: Bin Meng <bmeng.cn@gmail.com>
>> Cc: Marek Vasut <marex@denx.de>
>> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
>> ---
>> v2:
>> - Rework code a bit as suggested by Simon. Also added some comments
>>    to make the use of the code paths more clear.
>
>
> While this works I'm reluctant to commit it as is. The call to
> fdt_parent_offset() is very slow.

You've mentioned this before. But how slow could this function really 
be? And it should not be called that often via dev_get_addr(). Usually 
only once for each driver in the probe function. Or am I missing something?

> I wonder if this code should be copied into a new file in
> drivers/core/, tidied up and updated to use dev->parent?

You mean fdt_translate_address()? It references many functions from 
fdt_support.c though which we would need to duplicate here as well.

> Other options:
> - Add a library to unflatten the tree - but this would not be very
> useful in SPL or before relocation due to memory/speed constraints
> - Add a helper to find a node parent which uses a cached tree scan to
> build a table of previous nodes (or some other means to go backwards
> in the tree)
> - Worry about it later and go ahead with this patch

I see no problems to defer this patch (or a "better" version of it) to 
after this release. The Marvell mvebu DM patches are also not targeted 
for this release.

Thanks,
Stefan