u-boot/drivers/core/Kconfig

config DM
	bool "Enable Driver Model"
	help
	  This config option enables Driver Model. This brings in the core
	  support, including scanning of platform data on start-up. If
	  CONFIG_OF_CONTROL is enabled, the device tree will be scanned also
	  when available.

config SPL_DM
	bool "Enable Driver Model for SPL"
	depends on DM && SPL
	help
	  Enable driver model in SPL. You will need to provide a
	  suitable malloc() implementation. If you are not using the
	  full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START,
	  consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you
	  must provide CONFIG_SYS_MALLOC_F_LEN to set the size.
	  In most cases driver model will only allocate a few uclasses
	  and devices in SPL, so 1KB should be enable. See
	  CONFIG_SYS_MALLOC_F_LEN for more details on how to enable it.

config DM_WARN
	bool "Enable warnings in driver model"
	depends on DM
	default y
	help
	  The dm_warn() function can use up quite a bit of space for its
	  strings. By default this is disabled for SPL builds to save space.
	  This will cause dm_warn() to be compiled out - it will do nothing
	  when called.

config DM_DEVICE_REMOVE
	bool "Support device removal"
	depends on DM
	default y
	help
	  We can save some code space by dropping support for removing a
	  device. This is not normally required in SPL, so by default this
	  option is disabled for SPL.

config DM_STDIO
	bool "Support stdio registration"
	depends on DM
	default y
	help
	  Normally serial drivers register with stdio so that they can be used
	  as normal output devices. In SPL we don't normally use stdio, so
	  we can omit this feature.