For chips that don't have any meaningful boot-selection pins that directly change the Boot ROM's boot-order (e.g. Rockchip RK3399, Allwinner A64, Allwinner A80), a probing of devices in a predefined (and board-specfic) boot-order is desirable for the SPL to mimic the ROM's behaviour and allow overrides of the sequence according to user-defined policies.
To get the ball rolling, this has been implemented for the RK3399 in the board's SPL support, but I fully expect this to be generalised for other boards in the common SPL code (in a code-path dependent on DM, OF_CONTROL and BLK): unlike the current selection of a limited number of boot-devices (e.g. only a single BOOT_DEVICE_SPI), a more flexible approach (e.g. multiple SPI flashes to be probed in sequence) could then be realised.
These changes should be used in conjunction with FIT images (and all legacy image formats disabled via Kconfig).
Philipp Tomsich (1): rockchip: rk3399: spl: make SPL boot-order configurable via /chosen
arch/arm/mach-rockchip/rk3399-board-spl.c | 99 +++++++++++++++++++++++++++++++ doc/device-tree-bindings/chosen.txt | 22 +++++++ 2 files changed, 121 insertions(+)