Using below configs, the compile will have error: ERROR: "ehci_init_driver" undefined! .config: CONFIG_USB_CHIPIDEA=m CONFIG_USB_CHIPIDEA_HOST=y CONFIG_USB_CHIPIDEA_DEBUG=y The reason is chipidea host uses symbol from ehci, but ehci is not compiled. Let the chipidea host depend on ehci even it is built as module. Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxxxxx> --- drivers/usb/chipidea/Kconfig | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/chipidea/Kconfig b/drivers/usb/chipidea/Kconfig index eb2aa2e..d1bd8ef 100644 --- a/drivers/usb/chipidea/Kconfig +++ b/drivers/usb/chipidea/Kconfig @@ -12,7 +12,7 @@ if USB_CHIPIDEA config USB_CHIPIDEA_UDC bool "ChipIdea device controller" - depends on USB_GADGET=y || USB_CHIPIDEA=m + depends on USB_GADGET=y || (USB_CHIPIDEA=m && USB_GADGET=m) help Say Y here to enable device controller functionality of the ChipIdea driver. @@ -20,7 +20,7 @@ config USB_CHIPIDEA_UDC config USB_CHIPIDEA_HOST bool "ChipIdea host controller" depends on USB=y - depends on USB_EHCI_HCD=y || USB_CHIPIDEA=m + depends on USB_EHCI_HCD=y || (USB_CHIPIDEA=m && USB_EHCI_HCD=m) select USB_EHCI_ROOT_HUB_TT help Say Y here to enable host controller functionality of the -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html