fbdev: Make fb-notify a no-op if CONFIG_FB=n

There's no point in having support for framebuffer notifications
is CONFIG_FB is disabled. This commit adds the necessary stubs
for code to link properly when CONFIG_FB=n and moves fb-notify.o
to be built only when CONFIG_FB=y.
Signed-off-by: NEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/Kconfig

@@ -5,6 +5,7 @@
 menuconfig FB
 	tristate "Support for frame buffer devices"
 	select FB_CMDLINE
+	select FB_NOTIFY
 	---help---
 	  The frame buffer device provides an abstraction for the graphics
 	  hardware. It represents the frame buffer of some video hardware and
@@ -56,6 +57,9 @@ config FIRMWARE_EDID
 config FB_CMDLINE
 	bool
 
+config FB_NOTIFY
+	bool
+
 config FB_DDC
        tristate
        depends on FB

drivers/video/fbdev/core/Makefile

-obj-y                             += fb_notify.o
 obj-$(CONFIG_FB_CMDLINE)          += fb_cmdline.o
+obj-$(CONFIG_FB_NOTIFY)           += fb_notify.o
 obj-$(CONFIG_FB)                  += fb.o
 fb-y                              := fbmem.o fbmon.o fbcmap.o fbsysfs.o \
                                      modedb.o fbcvt.o

include/linux/fb.h

@@ -175,9 +175,27 @@ struct fb_blit_caps {
 	u32 flags;
 };
 
+#ifdef CONFIG_FB_NOTIFY
 extern int fb_register_client(struct notifier_block *nb);
 extern int fb_unregister_client(struct notifier_block *nb);
 extern int fb_notifier_call_chain(unsigned long val, void *v);
+#else
+static inline int fb_register_client(struct notifier_block *nb)
+{
+	return 0;
+};
+
+static inline int fb_unregister_client(struct notifier_block *nb)
+{
+	return 0;
+};
+
+static inline int fb_notifier_call_chain(unsigned long val, void *v)
+{
+	return 0;
+};
+#endif
+
 /*
  * Pixmap structure definition
  *