6.4.2. barebox deep probe properties

A barebox,deep-probe property in the top-level node indicates to barebox that the barebox board and device drivers support recursively probing devices on demand (deep probe).

For drivers to support deep probe, they must not rely on initcall ordering. Resources needed by drivers should be referenced via device tree, e.g., instead of direct use of hardcoded GPIO numbers, GPIOs must either be:

• described in the device’s device tree node and requested using API that that takes the device or the device tree node as argument

• probe of the GPIO controller be ensured via of_device_ensure_probed, e.g., of_devices_ensure_probed_by_property("gpio-controller");

The inverted flag is barebox,disable-deep-probe, which means that the board is not deep probe capable (or tested) yet.

The barebox,disable-deep-probe property takes precedence over barebox,deep-probe, but not over BAREBOX_DEEP_PROBE_ENABLE in the board code.

If neither property exists, the default deep probe behavior depends on the CONFIG_DEEP_PROBE_DEFAULT variable.

/ { /* SoM Device Tree */
     barebox,deep-probe;
};

/ { /* Board Device Tree */
     /* FIXME: While the SoM supports deep probe, our board code is broken
      * currently, so override until it's fixed
      */
     barebox,disable-deep-probe;
};