From: Ondrej Jirman <megous@megous.com>
Date: Sun, 17 Oct 2021 12:46:01 +0200
Subject: [PATCH 10/36] video: fbdev: Add events for early fb event support

This patch adds 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 <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/video/fbdev/core/fbmem.c | 12 +++++++++++-
 include/linux/fb.h               |  5 +++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 826175a..fb1651a 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1067,7 +1067,7 @@ int
 fb_blank(struct fb_info *info, int blank)
 {
 	struct fb_event event;
-	int ret = -EINVAL;
+	int ret = -EINVAL, early_ret;
 
 	if (blank > FB_BLANK_POWERDOWN)
 		blank = FB_BLANK_POWERDOWN;
@@ -1075,11 +1075,21 @@ fb_blank(struct fb_info *info, int blank)
 	event.info = info;
 	event.data = &blank;
 
+	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)
 		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;
 }
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 6f3db99..ffef502a 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -137,6 +137,11 @@ struct fb_cursor_user {
 /*      A display blank is requested       */
 #define FB_EVENT_BLANK                  0x09
 
+/*      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;
 	void *data;