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, 85 insertions, 18 deletions

diff --git a/drivers/video/fbdev/core/fb_backlight.c b/drivers/video/fbdev/core/fb_backlight.c
index 6fdaa9f81be9..dbed9696f4c5 100644
--- a/drivers/video/fbdev/core/fb_backlight.c
+++ b/drivers/video/fbdev/core/fb_backlight.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <linux/backlight.h>
 #include <linux/export.h>
 #include <linux/fb.h>
 #include <linux/mutex.h>
@@ -36,4 +37,15 @@ struct backlight_device *fb_bl_device(struct fb_info *info)
 	return info->bl_dev;
 }
 EXPORT_SYMBOL(fb_bl_device);
+
+void fb_bl_notify_blank(struct fb_info *info, int old_blank)
+{
+	bool on = info->blank == FB_BLANK_UNBLANK;
+	bool prev_on = old_blank == FB_BLANK_UNBLANK;
+
+	if (info->bl_dev)
+		backlight_notify_blank(info->bl_dev, info->device, on, prev_on);
+	else
+		backlight_notify_blank_all(info->device, on, prev_on);
+}
 #endif
diff --git a/drivers/video/fbdev/core/fb_info.c b/drivers/video/fbdev/core/fb_info.c
index 4847ebe50d7d..52f9bd2c5417 100644
--- a/drivers/video/fbdev/core/fb_info.c
+++ b/drivers/video/fbdev/core/fb_info.c
@@ -42,6 +42,7 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
 
 	info->device = dev;
 	info->fbcon_rotate_hint = -1;
+	info->blank = FB_BLANK_UNBLANK;
 
 #if IS_ENABLED(CONFIG_FB_BACKLIGHT)
 	mutex_init(&info->bl_curve_mutex);
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index eca2498f2436..dfcf5e4d1d4c 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -15,6 +15,8 @@
 #include <linux/export.h>
 #include <linux/fb.h>
 #include <linux/fbcon.h>
+#include <linux/lcd.h>
+#include <linux/leds.h>
 
 #include <video/nomodeset.h>
 
@@ -220,6 +222,12 @@ static int fb_check_caps(struct fb_info *info, struct fb_var_screeninfo *var,
 	return err;
 }
 
+static void fb_lcd_notify_mode_change(struct fb_info *info,
+				      struct fb_videomode *mode)
+{
+	lcd_notify_mode_change_all(info->device, mode->xres, mode->yres);
+}
+
 int
 fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 {
@@ -227,7 +235,6 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 	u32 activate;
 	struct fb_var_screeninfo old_var;
 	struct fb_videomode mode;
-	struct fb_event event;
 	u32 unused;
 
 	if (var->activate & FB_ACTIVATE_INV_MODE) {
@@ -333,32 +340,71 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 		return ret;
 	}
 
-	event.info = info;
-	event.data = &mode;
-	fb_notifier_call_chain(FB_EVENT_MODE_CHANGE, &event);
+	fb_lcd_notify_mode_change(info, &mode);
 
 	return 0;
 }
 EXPORT_SYMBOL(fb_set_var);
 
-int
-fb_blank(struct fb_info *info, int blank)
+static void fb_lcd_notify_blank(struct fb_info *info)
 {
-	struct fb_event event;
-	int ret = -EINVAL;
+	int power;
+
+	switch (info->blank) {
+	case FB_BLANK_UNBLANK:
+		power = LCD_POWER_ON;
+		break;
+	/* deprecated; TODO: should become 'off' */
+	case FB_BLANK_NORMAL:
+		power = LCD_POWER_REDUCED;
+		break;
+	case FB_BLANK_VSYNC_SUSPEND:
+		power = LCD_POWER_REDUCED_VSYNC_SUSPEND;
+		break;
+	/* 'off' */
+	case FB_BLANK_HSYNC_SUSPEND:
+	case FB_BLANK_POWERDOWN:
+	default:
+		power = LCD_POWER_OFF;
+		break;
+	}
+
+	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;
+	int ret;
+
+	if (!info->fbops->fb_blank)
+		return -EINVAL;
 
 	if (blank > FB_BLANK_POWERDOWN)
 		blank = FB_BLANK_POWERDOWN;
 
-	event.info = info;
-	event.data = &blank;
+	info->blank = blank;
 
-	if (info->fbops->fb_blank)
-		ret = info->fbops->fb_blank(blank, info);
+	ret = info->fbops->fb_blank(blank, info);
+	if (ret)
+		goto err;
+
+	fb_bl_notify_blank(info, old_blank);
+	fb_lcd_notify_blank(info);
+	fb_ledtrig_backlight_notify_blank(info);
 
-	if (!ret)
-		fb_notifier_call_chain(FB_EVENT_BLANK, &event);
+	return 0;
 
+err:
+	info->blank = old_blank;
 	return ret;
 }
 EXPORT_SYMBOL(fb_blank);
@@ -416,6 +462,14 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 	mutex_init(&fb_info->lock);
 	mutex_init(&fb_info->mm_lock);
 
+	/*
+	 * With an fb_blank callback present, we assume that the
+	 * display is blank, so that fb_blank() enables it on the
+	 * first modeset.
+	 */
+	if (fb_info->fbops->fb_blank)
+		fb_info->blank = FB_BLANK_POWERDOWN;
+
 	fb_device_create(fb_info);
 
 	if (fb_info->pixmap.addr == NULL) {
diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c
index 06d75c767579..b8344c40073b 100644
--- a/drivers/video/fbdev/core/fbsysfs.c
+++ b/drivers/video/fbdev/core/fbsysfs.c
@@ -242,11 +242,11 @@ static ssize_t store_blank(struct device *device,
 	return count;
 }
 
-static ssize_t show_blank(struct device *device,
-			  struct device_attribute *attr, char *buf)
+static ssize_t show_blank(struct device *device, struct device_attribute *attr, char *buf)
 {
-//	struct fb_info *fb_info = dev_get_drvdata(device);
-	return 0;
+	struct fb_info *fb_info = dev_get_drvdata(device);
+
+	return sysfs_emit(buf, "%d\n", fb_info->blank);
 }
 
 static ssize_t store_console(struct device *device,