[PATCH] USB: cdc_subset: only build when one driver is enabled

From: Arnd Bergmann
Date: Wed Feb 17 2016 - 17:26:24 EST


This avoids a harmless randconfig warning I get when USB_NET_CDC_SUBSET
is enabled, but all of the more specific drivers are not:

drivers/net/usb/cdc_subset.c:241:2: #warning You need to configure some hardware for this driver

The current behavior is clearly intentional, giving a warning when
a user picks a configuration that won't do anything good. The only
reason for even addressing this is that I'm getting close to
eliminating all 'randconfig' warnings on ARM, and this came up
a couple of times.

My workaround is to not even build the module when none of the
configurations are enable.

Alternatively we could simply remove the #warning (nothing wrong
for compile-testing), turn it into a runtime warning, or
change the Kconfig options into a menu to hide CONFIG_USB_NET_CDC_SUBSET.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/net/usb/Kconfig | 10 ++++++++++
drivers/net/usb/Makefile | 2 +-
2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index 7f83504dfa69..cdde59089f72 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -395,6 +395,10 @@ config USB_NET_RNDIS_HOST
The protocol specification is incomplete, and is controlled by
(and for) Microsoft; it isn't an "Open" ecosystem or market.

+config USB_NET_CDC_SUBSET_ENABLE
+ tristate
+ depends on USB_NET_CDC_SUBSET
+
config USB_NET_CDC_SUBSET
tristate "Simple USB Network Links (CDC Ethernet subset)"
depends on USB_USBNET
@@ -413,6 +417,7 @@ config USB_NET_CDC_SUBSET
config USB_ALI_M5632
bool "ALi M5632 based 'USB 2.0 Data Link' cables"
depends on USB_NET_CDC_SUBSET
+ select USB_NET_CDC_SUBSET_ENABLE
help
Choose this option if you're using a host-to-host cable
based on this design, which supports USB 2.0 high speed.
@@ -420,6 +425,7 @@ config USB_ALI_M5632
config USB_AN2720
bool "AnchorChips 2720 based cables (Xircom PGUNET, ...)"
depends on USB_NET_CDC_SUBSET
+ select USB_NET_CDC_SUBSET_ENABLE
help
Choose this option if you're using a host-to-host cable
based on this design. Note that AnchorChips is now a
@@ -428,6 +434,7 @@ config USB_AN2720
config USB_BELKIN
bool "eTEK based host-to-host cables (Advance, Belkin, ...)"
depends on USB_NET_CDC_SUBSET
+ select USB_NET_CDC_SUBSET_ENABLE
default y
help
Choose this option if you're using a host-to-host cable
@@ -437,6 +444,7 @@ config USB_BELKIN
config USB_ARMLINUX
bool "Embedded ARM Linux links (iPaq, ...)"
depends on USB_NET_CDC_SUBSET
+ select USB_NET_CDC_SUBSET_ENABLE
default y
help
Choose this option to support the "usb-eth" networking driver
@@ -454,6 +462,7 @@ config USB_ARMLINUX
config USB_EPSON2888
bool "Epson 2888 based firmware (DEVELOPMENT)"
depends on USB_NET_CDC_SUBSET
+ select USB_NET_CDC_SUBSET_ENABLE
help
Choose this option to support the usb networking links used
by some sample firmware from Epson.
@@ -461,6 +470,7 @@ config USB_EPSON2888
config USB_KC2190
bool "KT Technology KC2190 based cables (InstaNet)"
depends on USB_NET_CDC_SUBSET
+ select USB_NET_CDC_SUBSET_ENABLE
help
Choose this option if you're using a host-to-host cable
with one of these chips.
diff --git a/drivers/net/usb/Makefile b/drivers/net/usb/Makefile
index b5f04068dbe4..37fb46aee341 100644
--- a/drivers/net/usb/Makefile
+++ b/drivers/net/usb/Makefile
@@ -23,7 +23,7 @@ obj-$(CONFIG_USB_NET_GL620A) += gl620a.o
obj-$(CONFIG_USB_NET_NET1080) += net1080.o
obj-$(CONFIG_USB_NET_PLUSB) += plusb.o
obj-$(CONFIG_USB_NET_RNDIS_HOST) += rndis_host.o
-obj-$(CONFIG_USB_NET_CDC_SUBSET) += cdc_subset.o
+obj-$(CONFIG_USB_NET_CDC_SUBSET_ENABLE) += cdc_subset.o
obj-$(CONFIG_USB_NET_ZAURUS) += zaurus.o
obj-$(CONFIG_USB_NET_MCS7830) += mcs7830.o
obj-$(CONFIG_USB_USBNET) += usbnet.o
--
2.7.0