Re: [PATCH 03/28] of: create unflatten_and_copy_device_tree

[Vineet Gupta <Vineet.Gupta1@synopsys.com>]

On 09/17/2013 04:38 AM, Rob Herring wrote:
> From: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
> 
> Several architectures using DT support built-in dtb's in the init
> section. These platforms need to copy the dtb from init since the
> strings are referenced after unflattening. Every arch has their own
> copying routine which do the same thing. Create a common function,
> unflatten_and_copy_device_tree, to copy the dtb when unflattening the
> dtb.
> 
> Signed-off-by: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
> Cc: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  drivers/of/fdt.c       | 13 +++++++++++++
>  include/linux/of_fdt.h |  2 ++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 229dd9d..eca1810 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -802,6 +802,19 @@ void __init unflatten_device_tree(void)
>  	of_alias_scan(early_init_dt_alloc_memory_arch);
>  }
>  
> +void __init unflatten_and_copy_device_tree(void)
> +{

Can we add a comment here why exactly is the copy needed (unflattening doesn't
copy strings which are referenced to by the DT APIs). Will help first time readers.


> +	int size = __be32_to_cpu(initial_boot_params->totalsize);
> +	void *dt = early_init_dt_alloc_memory_arch(size,
> +		__alignof__(struct boot_param_header));
> +
> +	if (dt) {
> +		memcpy(dt, initial_boot_params, size);
> +		initial_boot_params = dt;
> +	}
> +	unflatten_device_tree();
> +}
> +
>  #endif /* CONFIG_OF_EARLY_FLATTREE */
>