leds: backlight trigger: Replace fb events with a dedicated function call

Remove support for fb events from the led backlight trigger. Provide
the helper ledtrig_backlight_blank() instead. Call it from fbdev to
inform the trigger of changes to a display's blank state.

Fbdev maintains a list of all installed notifiers. Instead of the fbdev
notifiers, maintain an internal list of led backlight triggers.

v3:
- export ledtrig_backlight_blank()
v2:
- maintain global list of led backlight triggers (Lee)
- avoid IS_REACHABLE() in source file (Lee)
- notify on changes to blank state instead of display state
- use lock guards
- initialize led list and list mutex

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20250321095517.313713-11-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>

1 files changed, 10 insertions, 9 deletions

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 001662c606d7..f089f72ec75a 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -16,6 +16,7 @@
 #include <linux/fb.h>
 #include <linux/fbcon.h>
 #include <linux/lcd.h>
+#include <linux/leds.h>
 
 #include <video/nomodeset.h>
 
@@ -369,11 +370,17 @@ static void fb_lcd_notify_blank(struct fb_info *info)
 	lcd_notify_blank_all(info->device, power);
 }
 
+static void fb_ledtrig_backlight_notify_blank(struct fb_info *info)
+{
+	if (info->blank == FB_BLANK_UNBLANK)
+		ledtrig_backlight_blank(false);
+	else
+		ledtrig_backlight_blank(true);
+}
+
 int fb_blank(struct fb_info *info, int blank)
 {
 	int old_blank = info->blank;
-	struct fb_event event;
-	int data[2];
 	int ret;
 
 	if (!info->fbops->fb_blank)
@@ -382,11 +389,6 @@ int fb_blank(struct fb_info *info, int blank)
 	if (blank > FB_BLANK_POWERDOWN)
 		blank = FB_BLANK_POWERDOWN;
 
-	data[0] = blank;
-	data[1] = old_blank;
-	event.info = info;
-	event.data = data;
-
 	info->blank = blank;
 
 	ret = info->fbops->fb_blank(blank, info);
@@ -395,8 +397,7 @@ int fb_blank(struct fb_info *info, int blank)
 
 	fb_bl_notify_blank(info, old_blank);
 	fb_lcd_notify_blank(info);
-
-	fb_notifier_call_chain(FB_EVENT_BLANK, &event);
+	fb_ledtrig_backlight_notify_blank(info);
 
 	return 0;