Merge tag 'backlight-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight

Pull backlight updates from Lee Jones:
 "Framebuffer Subsystem (fbdev):
   - The display's blanking status is now tracked in 'struct fb_info'
   - 'framebuffer_alloc()' initializes the blank state to FB_BLANK_UNBLANK
   - 'register_framebuffer()' sets the state to 'FB_BLANK_POWERDOWN' if
     an 'fb_blank' callback exists, ensuring 'FB_EVENT_BLANK' listeners
     correctly see the display being turned on during the first modeset
   - The 'FB_EVENT_BLANK' event data now includes both the new and the
     old blank states
   - 'fb_blank()' has been reworked to return early on errors, without
     functional changes, in preparation for further state tracking
     improvements
   - Fbdev now calls dedicated functions in the backlight subsystems to
     notify them of blank state changes, instead of relying on fbdev
     event notifiers
   - For LCDs, fbdev also calls a dedicated function to notify of mode
     changes
   - Removed the definitions for the unused fbdev event constants
     'FB_EVENT_MODE_CHANGE' and 'FB_EVENT_BLANK' from the header file

  Backlight Subsystem:
   - Implemented fbdev blank state tracking using the (newly enhanced)
     blank state information provided directly by 'FB_EVENT_BLANK'
   - Removed internal blank state tracking fields ('fb_bl_on') from
     'struct backlight_device'
   - Moved the handling of blank-state updates into a separate internal
     helper function, 'backlight_notify_blank()'
   - Removed support for fbdev events and replaced it with a dedicated
     function call interface ('backlight_notify_blank()' and
     'backlight_notify_blank_all()') for display drivers to update
     backlight status

  LCD Subsystem:
   - Moved the handling of display updates (blank events and mode
     changes) from fbdev event notifiers to separate internal helper
     functions ('lcd_notify_blank',
     'lcd_notify_mode_change')
   - Removed support for fbdev events and replaced it with dedicated
     function call interfaces ('lcd_notify_blank_all()',
     'lcd_notify_mode_change_all()')
   - The LCD subsystem now maintains its own internal list of LCD
     devices instead of relying on fbdev notifiers

  LED Backlight Trigger:
   - Moved the handling of blank-state updates into a separate internal
     helper, 'ledtrig_backlight_notify_blank()'
   - Removed support for fbdev events and replaced it with a dedicated
     function call, 'ledtrig_backlight_blank()', for fbdev to notify
     trigger of blank state changes
   - The LED backlight trigger now maintains its own internal list of
     triggers instead of relying on fbdev notifiers

  Qualcomm WLED Backlight:
   - Added a NULL check after 'devm_kasprintf()' in 'wled_configure()'
     to prevent a potential NULL pointer dereference if memory
     allocation fails"

* tag 'backlight-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: pm8941: Add NULL check in wled_configure()
  fbdev: Remove constants of unused events
  leds: backlight trigger: Replace fb events with a dedicated function call
  leds: backlight trigger: Move blank-state handling into helper
  backlight: lcd: Replace fb events with a dedicated function call
  backlight: lcd: Move event handling into helpers
  backlight: Replace fb events with a dedicated function call
  backlight: Move blank-state handling into helper
  backlight: Implement fbdev tracking with blank state from event
  fbdev: Send old blank state in FB_EVENT_BLANK
  fbdev: Track display blanking state
  fbdev: Rework fb_blank()

1 files changed, 23 insertions, 25 deletions

diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 487577d22cfc..c1f0f5becaee 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -10,7 +10,6 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/init.h>
-#include <linux/fb.h>
 #include <linux/leds.h>
 #include "../leds.h"
 
@@ -21,29 +20,20 @@ struct bl_trig_notifier {
 	struct led_classdev *led;
 	int brightness;
 	int old_status;
-	struct notifier_block notifier;
 	unsigned invert;
+
+	struct list_head entry;
 };
 
-static int fb_notifier_callback(struct notifier_block *p,
-				unsigned long event, void *data)
+static DEFINE_MUTEX(ledtrig_backlight_list_mutex);
+static LIST_HEAD(ledtrig_backlight_list);
+
+static void ledtrig_backlight_notify_blank(struct bl_trig_notifier *n, int new_status)
 {
-	struct bl_trig_notifier *n = container_of(p,
-					struct bl_trig_notifier, notifier);
 	struct led_classdev *led = n->led;
-	struct fb_event *fb_event = data;
-	int *blank;
-	int new_status;
-
-	/* If we aren't interested in this event, skip it immediately ... */
-	if (event != FB_EVENT_BLANK)
-		return 0;
-
-	blank = fb_event->data;
-	new_status = *blank ? BLANK : UNBLANK;
 
 	if (new_status == n->old_status)
-		return 0;
+		return;
 
 	if ((n->old_status == UNBLANK) ^ n->invert) {
 		n->brightness = led->brightness;
@@ -53,9 +43,19 @@ static int fb_notifier_callback(struct notifier_block *p,
 	}
 
 	n->old_status = new_status;
+}
 
-	return 0;
+void ledtrig_backlight_blank(bool blank)
+{
+	struct bl_trig_notifier *n;
+	int new_status = blank ? BLANK : UNBLANK;
+
+	guard(mutex)(&ledtrig_backlight_list_mutex);
+
+	list_for_each_entry(n, &ledtrig_backlight_list, entry)
+		ledtrig_backlight_notify_blank(n, new_status);
 }
+EXPORT_SYMBOL(ledtrig_backlight_blank);
 
 static ssize_t bl_trig_invert_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -100,8 +100,6 @@ ATTRIBUTE_GROUPS(bl_trig);
 
 static int bl_trig_activate(struct led_classdev *led)
 {
-	int ret;
-
 	struct bl_trig_notifier *n;
 
 	n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
@@ -112,11 +110,9 @@ static int bl_trig_activate(struct led_classdev *led)
 	n->led = led;
 	n->brightness = led->brightness;
 	n->old_status = UNBLANK;
-	n->notifier.notifier_call = fb_notifier_callback;
 
-	ret = fb_register_client(&n->notifier);
-	if (ret)
-		dev_err(led->dev, "unable to register backlight trigger\n");
+	guard(mutex)(&ledtrig_backlight_list_mutex);
+	list_add(&n->entry, &ledtrig_backlight_list);
 
 	return 0;
 }
@@ -125,7 +121,9 @@ static void bl_trig_deactivate(struct led_classdev *led)
 {
 	struct bl_trig_notifier *n = led_get_trigger_data(led);
 
-	fb_unregister_client(&n->notifier);
+	guard(mutex)(&ledtrig_backlight_list_mutex);
+	list_del(&n->entry);
+
 	kfree(n);
 }