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()

4 files changed, 47 insertions, 24 deletions

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index f5652e5a9060..10e626db7eee 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -12,7 +12,6 @@
 #include <linux/device.h>
 #include <linux/fb.h>
 #include <linux/mutex.h>
-#include <linux/notifier.h>
 #include <linux/types.h>
 
 /**
@@ -279,11 +278,6 @@ struct backlight_device {
 	const struct backlight_ops *ops;
 
 	/**
-	 * @fb_notif: The framebuffer notifier block
-	 */
-	struct notifier_block fb_notif;
-
-	/**
 	 * @entry: List entry of all registered backlight devices
 	 */
 	struct list_head entry;
@@ -294,15 +288,7 @@ struct backlight_device {
 	struct device dev;
 
 	/**
-	 * @fb_bl_on: The state of individual fbdev's.
-	 *
-	 * Multiple fbdev's may share one backlight device. The fb_bl_on
-	 * records the state of the individual fbdev.
-	 */
-	bool fb_bl_on[FB_MAX];
-
-	/**
-	 * @use_count: The number of uses of fb_bl_on.
+	 * @use_count: The number of unblanked displays.
 	 */
 	int use_count;
 };
@@ -408,6 +394,22 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
 int backlight_device_set_brightness(struct backlight_device *bd,
 				    unsigned long brightness);
 
+#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE)
+void backlight_notify_blank(struct backlight_device *bd,
+			    struct device *display_dev,
+			    bool fb_on, bool prev_fb_on);
+void backlight_notify_blank_all(struct device *display_dev,
+				bool fb_on, bool prev_fb_on);
+#else
+static inline void backlight_notify_blank(struct backlight_device *bd,
+					  struct device *display_dev,
+					  bool fb_on, bool prev_fb_on)
+{ }
+static inline void backlight_notify_blank_all(struct device *display_dev,
+					      bool fb_on, bool prev_fb_on)
+{ }
+#endif
+
 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 
 /**
diff --git a/include/linux/fb.h b/include/linux/fb.h
index cd653862ab99..05cc251035da 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -129,18 +129,12 @@ struct fb_cursor_user {
  * Register/unregister for framebuffer events
  */
 
-/*	The resolution of the passed in fb_info about to change */
-#define FB_EVENT_MODE_CHANGE		0x01
-
 #ifdef CONFIG_GUMSTIX_AM200EPD
 /* only used by mach-pxa/am200epd.c */
 #define FB_EVENT_FB_REGISTERED          0x05
 #define FB_EVENT_FB_UNREGISTERED        0x06
 #endif
 
-/*      A display blank is requested       */
-#define FB_EVENT_BLANK                  0x09
-
 struct fb_event {
 	struct fb_info *info;
 	void *data;
@@ -472,6 +466,8 @@ struct fb_info {
 	struct list_head modelist;      /* mode list */
 	struct fb_videomode *mode;	/* current mode */
 
+	int blank; /* current blanking; see FB_BLANK_ constants */
+
 #if IS_ENABLED(CONFIG_FB_BACKLIGHT)
 	/* assigned backlight device */
 	/* set before framebuffer registration,
@@ -756,11 +752,15 @@ extern void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max)
 
 #if IS_ENABLED(CONFIG_FB_BACKLIGHT)
 struct backlight_device *fb_bl_device(struct fb_info *info);
+void fb_bl_notify_blank(struct fb_info *info, int old_blank);
 #else
 static inline struct backlight_device *fb_bl_device(struct fb_info *info)
 {
 	return NULL;
 }
+
+static inline void fb_bl_notify_blank(struct fb_info *info, int old_blank)
+{ }
 #endif
 
 static inline struct lcd_device *fb_lcd_device(struct fb_info *info)
diff --git a/include/linux/lcd.h b/include/linux/lcd.h
index c3ccdff4519a..d4fa03722b72 100644
--- a/include/linux/lcd.h
+++ b/include/linux/lcd.h
@@ -11,7 +11,6 @@
 
 #include <linux/device.h>
 #include <linux/mutex.h>
-#include <linux/notifier.h>
 
 #define LCD_POWER_ON			(0)
 #define LCD_POWER_REDUCED		(1) // deprecated; don't use in new code
@@ -79,8 +78,11 @@ struct lcd_device {
 	const struct lcd_ops *ops;
 	/* Serialise access to set_power method */
 	struct mutex update_lock;
-	/* The framebuffer notifier block */
-	struct notifier_block fb_notif;
+
+	/**
+	 * @entry: List entry of all registered lcd devices
+	 */
+	struct list_head entry;
 
 	struct device dev;
 };
@@ -125,6 +127,19 @@ extern void lcd_device_unregister(struct lcd_device *ld);
 extern void devm_lcd_device_unregister(struct device *dev,
 	struct lcd_device *ld);
 
+#if IS_REACHABLE(CONFIG_LCD_CLASS_DEVICE)
+void lcd_notify_blank_all(struct device *display_dev, int power);
+void lcd_notify_mode_change_all(struct device *display_dev,
+				unsigned int width, unsigned int height);
+#else
+static inline void lcd_notify_blank_all(struct device *display_dev, int power)
+{}
+
+static inline void lcd_notify_mode_change_all(struct device *display_dev,
+					      unsigned int width, unsigned int height)
+{}
+#endif
+
 #define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
 
 static inline void * lcd_get_data(struct lcd_device *ld_dev)
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 98f9719c924c..b3f0aa081064 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -640,6 +640,12 @@ static inline void ledtrig_flash_ctrl(bool on) {}
 static inline void ledtrig_torch_ctrl(bool on) {}
 #endif
 
+#if IS_REACHABLE(CONFIG_LEDS_TRIGGER_BACKLIGHT)
+void ledtrig_backlight_blank(bool blank);
+#else
+static inline void ledtrig_backlight_blank(bool blank) {}
+#endif
+
 /*
  * Generic LED platform data for describing LED names and default triggers.
  */