backlight: lcd: Test against struct fb_info.lcd_dev

Add struct fb_info.lcd_dev for fbdev drivers to store a reference to
their lcd device. Update the lcd's fb_notifier_callback() to test for
this field. The lcd module can now detect if an lcd device belongs to
an fbdev device.

This works similar to the bl_dev for backlights and will allow for
the removal of the check_fb callback from several fbdev driver's lcd
devices.

Signed-off-by: Thomas Zimmermann <[email protected]>
Reviewed-by: Daniel Thompson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lee Jones <[email protected]>

Author: tdz

drivers/video/backlight/lcd.c

@@ -30,13 +30,16 @@ static int fb_notifier_callback(struct notifier_block *self,
 	struct lcd_device *ld = container_of(self, struct lcd_device, fb_notif);
 	struct fb_event *evdata = data;
 	struct fb_info *info = evdata->info;
+	struct lcd_device *fb_lcd = fb_lcd_device(info);
 
 	guard(mutex)(&ld->ops_lock);
 
 	if (!ld->ops)
 		return 0;
 	if (ld->ops->check_fb && !ld->ops->check_fb(ld, info))
 		return 0;
+	if (fb_lcd && fb_lcd != ld)
+		return 0;
 
 	if (event == FB_EVENT_BLANK) {
 		if (ld->ops->set_power)

include/linux/fb.h

@@ -21,6 +21,7 @@ struct fb_info;
 struct file;
 struct i2c_adapter;
 struct inode;
+struct lcd_device;
 struct module;
 struct notifier_block;
 struct page;
@@ -480,6 +481,13 @@ struct fb_info {
 	struct mutex bl_curve_mutex;
 	u8 bl_curve[FB_BACKLIGHT_LEVELS];
 #endif
+
+	/*
+	 * Assigned LCD device; set before framebuffer
+	 * registration, remove after unregister
+	 */
+	struct lcd_device *lcd_dev;
+
 #ifdef CONFIG_FB_DEFERRED_IO
 	struct delayed_work deferred_work;
 	unsigned long npagerefs;
@@ -754,6 +762,11 @@ static inline struct backlight_device *fb_bl_device(struct fb_info *info)
 }
 #endif
 
+static inline struct lcd_device *fb_lcd_device(struct fb_info *info)
+{
+	return info->lcd_dev;
+}
+
 /* fbmon.c */
 #define FB_MAXTIMINGS		0
 #define FB_VSYNCTIMINGS		1