From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Warren <swarren@wwwdotorg.org>
Date: Wed, 30 Sep 2015 10:13:20 -0600
Subject: [U-Boot] [PATCH v3] dm: core: Enable optional use of
 fdt_translate_address()
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 <1443589243-9521-1-git-send-email-sr@denx.de>
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On 09/29/2015 11:00 PM, Stefan Roese 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.

This change makes sense to me, but one comment:

> diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig

> +config OF_TRANSLATE
> +	bool "Translate addresses using fdt_translate_address"
> +	depends on DM && OF_CONTROL
> +	default y

So this is on by default, which I think is correct since applying this 
technique is required to parse DT correctly. However, ...

> diff --git a/drivers/core/device.c b/drivers/core/device.c

> +	if (CONFIG_IS_ENABLED(OF_TRANSLATE)) {

> +		/*
> +		 * Use the full-fledged translate function for complex
> +		 * bus setups.
> +		 */
> +		return fdt_translate_address((void *)gd->fdt_blob,
> +					     dev->of_offset, reg);

fdt_translate_address() is a simple wrapper around 
__of_translate_address(), and that function calls fdt_parent_offset() 
which is "slow" per Simon. Surely this patch will receive the same 
objection as when I added a (single) call to fdt_parent_offset() into 
the DT address parsing routine (and this patch is worse, since it adds a 
call to fdt_parent_offset() for each level of DT sub-nodes).