fbdev: add events for early fb event support

Add FB_EARLY_EVENT_BLANK and FB_R_EARLY_EVENT_BLANK event mode supports.
first, fb_notifier_call_chain() is called with FB_EARLY_EVENT_BLANK and
fb_blank() of specific fb driver is called and then
fb_notifier_call_chain() is called with FB_EVENT_BLANK again at
fb_blank(). and if fb_blank() was failed then fb_nitifier_call_chain()
would be called with FB_R_EARLY_EVENT_BLANK to revert the previous
effects.

Signed-off-by: Inki Dae <[e-mail]>
Signed-off-by: Kyungmin Park <[e-mail]>
Cc: Lars-Peter Clausen <[e-mail]>
Acked-by: Florian Tobias Schandinat <[e-mail]>
Cc: Richard Purdie <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/fbmem.c

···
 int
 fb_blank(struct fb_info *info, int blank)
 {	
- 	int ret = -EINVAL;
+	struct fb_event event;
+	int ret = -EINVAL, early_ret;
 
  	if (blank > FB_BLANK_POWERDOWN)
  		blank = FB_BLANK_POWERDOWN;
 
+	event.info = info;
+	event.data = ␣
+
+	early_ret = fb_notifier_call_chain(FB_EARLY_EVENT_BLANK, &event);
+
 	if (info->fbops->fb_blank)
  		ret = info->fbops->fb_blank(blank, info);
 
- 	if (!ret) {
-		struct fb_event event;
-
-		event.info = info;
-		event.data = ␣
+	if (!ret)
 		fb_notifier_call_chain(FB_EVENT_BLANK, &event);
+	else {
+		/*
+		 * if fb_blank is failed then revert effects of
+		 * the early blank event.
+		 */
+		if (!early_ret)
+			fb_notifier_call_chain(FB_R_EARLY_EVENT_BLANK, &event);
 	}
 
  	return ret;

include/linux/fb.h

···
 #define FB_EVENT_FB_UNBIND              0x0E
 /*      CONSOLE-SPECIFIC: remap all consoles to new fb - for vga switcheroo */
 #define FB_EVENT_REMAP_ALL_CONSOLE      0x0F
+/*      A hardware display blank early change occured */
+#define FB_EARLY_EVENT_BLANK		0x10
+/*      A hardware display blank revert early change occured */
+#define FB_R_EARLY_EVENT_BLANK		0x11
 
 struct fb_event {
 	struct fb_info *info;