[U-Boot] [PATCH v3 09/14] doc: Document how to apply fdt overlays

[Łukasz Majewski]

On 09/04/2017 10:12 PM, Pantelis Antoniou wrote:
> We have the capability to apply overlays on the command line but
> we didn't have a document explaining how.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou at konsulko.com>
> ---
>   doc/README.fdt-overlays | 37 +++++++++++++++++++++++++++++++++++++
>   1 file changed, 37 insertions(+)
>   create mode 100644 doc/README.fdt-overlays
> 
> diff --git a/doc/README.fdt-overlays b/doc/README.fdt-overlays
> new file mode 100644
> index 0000000..ee868ec
> --- /dev/null
> +++ b/doc/README.fdt-overlays
> @@ -0,0 +1,37 @@
> +U-Boot FDT Overlay usage (without FIT images)
> +=============================================
> +
> +FDT overlays are now available for use even without FIT images.
> +It is not as automagic as with FIT images though and require a few
> +manual steps.
> +
> +1. Figure out where to place both the base device tree blob and the
> +overlay. Make sure you have enough space to grow the base tree without
> +overlapping anything.
> +
> +=> setenv fdtaddr 0x87f00000
> +=> setenv fdtovaddr 0x87fc0000
> +
> +2. Load the base blob and overlay blobs
> +
> +=> load ${devtype} ${bootpart} ${fdtaddr} ${bootdir}/base.dtb
> +=> load ${devtype} ${bootpart} ${fdtovaddr} ${bootdir}/overlay.dtb
> +
> +3. Set it as the working fdt tree.
> +
> +=> fdtaddr $fdtaddr
> +
> +4. Grow it enough so it can 'fit' all the applied overlays
> +
> +=> fdt resize 8192
> +
> +5. You are now ready to apply the overlay.
> +
> +=> fdt apply $fdtovaddr
> +
> +Please note that in case of an error, both the base and overlays are going
> +to be invalidated, so keep copies to avoid reloading.
> +
> +Pantelis Antoniou
> +pantelis.antoniou at konsulko.com
> +11/7/2017
> 

Reviewed-by: Łukasz Majewski

-- 
Best regards,

Lukasz Majewski

--

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