Hello, In order for spi_busnum_to_master to work spi master devices must be linked into the spi_master_class.subsys.kset list. At the moment the default class_obj_subsys.kset is used and we can't enumerate the master devices. Patch is updated to match the 2.6.18 kernel. Signed-off-by: Hans-Christian Egtvedt -- With kind regards, Hans-Christian Egtvedt Applications Engineer - AVR Applications Lab