xref: /rk3399_rockchip-uboot/doc/README.fdt-overlays (revision 994d9d06da2f0237dbf9b03801e11a1250fdebe6)
1U-Boot FDT Overlay usage (without FIT images)
2=============================================
3
4FDT overlays are now available for use even without FIT images.
5It is not as automagic as with FIT images though and require a few
6manual steps.
7
81. Figure out where to place both the base device tree blob and the
9overlay. Make sure you have enough space to grow the base tree without
10overlapping anything.
11
12=> setenv fdtaddr 0x87f00000
13=> setenv fdtovaddr 0x87fc0000
14
152. Load the base blob and overlay blobs
16
17=> load ${devtype} ${bootpart} ${fdtaddr} ${bootdir}/base.dtb
18=> load ${devtype} ${bootpart} ${fdtovaddr} ${bootdir}/overlay.dtb
19
203. Set it as the working fdt tree.
21
22=> fdtaddr $fdtaddr
23
244. Grow it enough so it can 'fit' all the applied overlays
25
26=> fdt resize 8192
27
285. You are now ready to apply the overlay.
29
30=> fdt apply $fdtovaddr
31
32Please note that in case of an error, both the base and overlays are going
33to be invalidated, so keep copies to avoid reloading.
34
35Pantelis Antoniou
36pantelis.antoniou@konsulko.com
3711/7/2017
38