[U-Boot] [PATCH 1/2] libfdt: overlay: Fix missing symbols condition

[Maxime Ripard]

On Thu, Dec 15, 2016 at 03:03:26PM -0800, Stefan Agner wrote:
> From: Stefan Agner <stefan.agner at toradex.com>
> 
> When there is no symbols section in the device tree,
> overlay_fixup_phandles should return FDT_ERR_NOTFOUND instead of
> FDT_ERR_BADOFFSET.
> 
> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
> ---
> 
>  lib/libfdt/fdt_overlay.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/libfdt/fdt_overlay.c b/lib/libfdt/fdt_overlay.c
> index bb41404..4a9ba40 100644
> --- a/lib/libfdt/fdt_overlay.c
> +++ b/lib/libfdt/fdt_overlay.c
> @@ -495,9 +495,9 @@ static int overlay_fixup_phandles(void *fdt, void *fdto)
>  	if ((fixups_off < 0 && (fixups_off != -FDT_ERR_NOTFOUND)))
>  		return fixups_off;
>  
> -	/* And base DTs without symbols */
> +	/* But if we need to fixup phandles, symbols are required */
>  	symbols_off = fdt_path_offset(fdt, "/__symbols__");
> -	if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
> +	if (symbols_off < 0)
>  		return symbols_off;

A base device tree doesn't need to have a symbols node. In the
(uncommon, true, but still real) case where you wouldn't have any
label in the base DT, __symbols__ wouldn't be there.

Now, that code would return an error only if there's such a reference
expressed in __fixups__, but no __symbols__ node that also has that
reference. This is definitely an error but not really a NOTFOUND. You
had an offset already, but this offset was bad. Hence the error.

Do you have a base DT and an overlay showing up the error you're
trying to fix? Either way, that should be discussed with upstream's
libfdt ml and maintainer, not (only) on U-Boot.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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