backlight: lcd: Replace check_fb with controls_device

Rename check_fb in struct lcd_ops to controls_device. The callback
is now independent from fbdev's struct fb_info and tests if an lcd
device controls a hardware display device. The new naming and semantics
follow similar functionality for backlight devices.

v2:
- fix typos in commit description (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20240906075439.98476-27-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Thomas Zimmermann

drivers/video/backlight/lcd.c

@@ -54,7 +54,7 @@ static int fb_notifier_callback(struct notifier_block *self,
 
 	if (!ld->ops)
 		return 0;
-	if (ld->ops->check_fb && !ld->ops->check_fb(ld, info))
+	if (ld->ops->controls_device && !ld->ops->controls_device(ld, info->device))
 		return 0;
 	if (fb_lcd && fb_lcd != ld)
 		return 0;

drivers/video/backlight/platform_lcd.c

@@ -9,7 +9,6 @@
 
 #include <linux/module.h>
 #include <linux/platform_device.h>
-#include <linux/fb.h>
 #include <linux/lcd.h>
 #include <linux/slab.h>
 
@@ -50,17 +49,17 @@ static int platform_lcd_set_power(struct lcd_device *lcd, int power)
 	return 0;
 }
 
-static int platform_lcd_match(struct lcd_device *lcd, struct fb_info *info)
+static bool platform_lcd_controls_device(struct lcd_device *lcd, struct device *display_device)
 {
 	struct platform_lcd *plcd = to_our_lcd(lcd);
 
-	return plcd->us->parent == info->device;
+	return plcd->us->parent == display_device;
 }
 
 static const struct lcd_ops platform_lcd_ops = {
-	.get_power	= platform_lcd_get_power,
-	.set_power	= platform_lcd_set_power,
-	.check_fb	= platform_lcd_match,
+	.get_power		= platform_lcd_get_power,
+	.set_power		= platform_lcd_set_power,
+	.controls_device	= platform_lcd_controls_device,
 };
 
 static int platform_lcd_probe(struct platform_device *pdev)

include/linux/lcd.h

@@ -35,7 +35,6 @@
  */
 
 struct lcd_device;
-struct fb_info;
 
 struct lcd_properties {
 	/* The maximum value for contrast (read-only) */
@@ -54,9 +53,18 @@ struct lcd_ops {
         int (*set_contrast)(struct lcd_device *, int contrast);
 	/* Set LCD panel mode (resolutions ...) */
 	int (*set_mode)(struct lcd_device *, struct fb_videomode *);
-	/* Check if given framebuffer device is the one LCD is bound to;
-	   return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
-	int (*check_fb)(struct lcd_device *, struct fb_info *);
+
+	/*
+	 * Check if the LCD controls the given display device. This
+	 * operation is optional and if not implemented it is assumed that
+	 * the display is always the one controlled by the LCD.
+	 *
+	 * RETURNS:
+	 *
+	 * If display_dev is NULL or display_dev matches the device controlled by
+	 * the LCD, return true. Otherwise return false.
+	 */
+	bool (*controls_device)(struct lcd_device *lcd, struct device *display_device);
 };
 
 struct lcd_device {