On Fri, 24 Jun 2016, Arnd Bergmann wrote:

On Friday, June 24, 2016 10:28:50 AM CEST Jiri Kosina wrote:

quoted

From: Jiri Kosina <redacted>

Use IS_ENABLED() for checking USB_HIDDEV to make sure compilation works 
for all possible config combinations.

Signed-off-by: Jiri Kosina <redacted>
---
 include/linux/hiddev.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/hiddev.h b/include/linux/hiddev.h
index a5dd814..b6f48d6 100644
--- a/include/linux/hiddev.h
+++ b/include/linux/hiddev.h

@@ -37,7 +37,7 @@ struct hid_usage;
 struct hid_field;
 struct hid_report;
 
-#ifdef CONFIG_USB_HIDDEV
+#if IS_ENABLED(CONFIG_USB_HIDDEV)
 int hiddev_connect(struct hid_device *hid, unsigned int force);
 void hiddev_disconnect(struct hid_device *);
 void hiddev_hid_event(struct hid_device *hid, struct hid_field *field,

CONFIG_USB_HIDDEV is a 'bool' option, so the two look completely
equivalent.

If we wanted to make USB_HIDDEV a loadable module by itself,
we'd also need to export those functions and change both the Kconfig
and Makefile files to ensure that you can't have USB_HIDDEV=m
in combination with USB_HID=y.

What problem are you trying to fix specifically?

This mail was by my mistake generated from my private git tree; sorry for 
the noise, feel free to ignore it.

-- 
Jiri Kosina
SUSE Labs