idxd sub-drivers belong to bus dsa_bus_type. Thus, dsa_bus_type must be registered in dsa bus init before idxd drivers can be registered. But the order is wrong when both idxd and idxd_bus are builtin drivers. In this case, idxd driver is compiled and linked before idxd_bus driver. Since the initcall order is determined by the link order, idxd sub-drivers are registered in idxd initcall before dsa_bus_type is registered in idxd_bus initcall. idxd initcall fails: [ 21.562803] calling idxd_init_module+0x0/0x110 @ 1 [ 21.570761] Driver 'idxd' was unable to register with bus_type 'dsa' because the bus was not initialized. [ 21.586475] initcall idxd_init_module+0x0/0x110 returned -22 after 15717 usecs [ 21.597178] calling dsa_bus_init+0x0/0x20 @ 1 To fix the issue, compile and link idxd_bus driver before idxd driver to ensure the right registration order. Fixes: d9e5481fca74 ("dmaengine: dsa: move dsa_bus_type out of idxd driver to standalone") Reported-by: Michael Prinke <michael.prinke@xxxxxxxxx> Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx> --- drivers/dma/idxd/Makefile | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/dma/idxd/Makefile b/drivers/dma/idxd/Makefile index dc096839ac63..c5e679070e46 100644 --- a/drivers/dma/idxd/Makefile +++ b/drivers/dma/idxd/Makefile @@ -1,12 +1,12 @@ ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=IDXD +obj-$(CONFIG_INTEL_IDXD_BUS) += idxd_bus.o +idxd_bus-y := bus.o + obj-$(CONFIG_INTEL_IDXD) += idxd.o idxd-y := init.o irq.o device.o sysfs.o submit.o dma.o cdev.o debugfs.o idxd-$(CONFIG_INTEL_IDXD_PERFMON) += perfmon.o -obj-$(CONFIG_INTEL_IDXD_BUS) += idxd_bus.o -idxd_bus-y := bus.o - obj-$(CONFIG_INTEL_IDXD_COMPAT) += idxd_compat.o idxd_compat-y := compat.o -- 2.37.1