diff options
Diffstat (limited to 'dts')
| -rw-r--r-- | dts/Kconfig | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/dts/Kconfig b/dts/Kconfig index 5dcc79d5192..e57ce84b98d 100644 --- a/dts/Kconfig +++ b/dts/Kconfig @@ -98,13 +98,36 @@ endchoice config OF_BOARD bool "Provided by the board (e.g a previous loader) at runtime" - default y if SANDBOX + default y if SANDBOX || OF_HAS_PRIOR_STAGE help - If this option is enabled, the device tree will be provided by - the board at runtime if the board supports it. The device tree bundled - with the image (if any) will be overridden / ignored. + If this option is enabled, the device tree is provided at runtime by + a custom function called board_fdt_blob_setup(). The board must + implement this function if it wishes to provide special behaviour. - A device tree file must be provided in the tree. + With this option, the device tree build by U-Boot may be overridden or + ignored. See OF_HAS_PRIOR_STAGE. + + Note: Boards which use this to handle a device tree passed from an + earlier stage should enable OF_HAS_PRIOR_STAGE. + +config OF_HAS_PRIOR_STAGE + bool + help + Indicates that a prior stage of the firmware (before U-Boot proper) + makes use of device tree and this board normally boots with that prior + stage, that provides a devicetree to U-Boot. + + This means that the device tree built in U-Boot should not be packaged + in the firmware image. Instead, the prior stage's device tree should + be so packaged. At runtime, the prior stage reads this, does any + necessary fix-ups, then passes it to U-Boot. See OF_BOARD. + + This option does not preclude using the U-Boot device tree, e.g. for + development purposes, but it is not recommended, and likely will not + even work, for production systems. + + Note: This option must be set in Kconfig and cannot be enabled or + disabled in the board's defconfig file. config DEFAULT_DEVICE_TREE string "Default Device Tree for DT control" |