== Changes to existing drivers ==

- Supply MODULE_DEVICE_TABLE() to ensure probing
  - Constify struct; da9052_bl
  - Enable compile test; lcd_l4f00242t03, lcd_lms283fg05, backlight_gpio
  - Suspend/resume bugfix; lp855x_bl
  - devm_gpiod_get_optional() API fixup; pwm_bl
  - Error handling fixup; backlight
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Merge tag 'backlight-for-linus-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight

Pull backlight updates from Lee Jones:
 "Changes to existing drivers:

   - supply MODULE_DEVICE_TABLE() to ensure probing
   - constify struct; da9052_bl
   - enable compile test; lcd_l4f00242t03, lcd_lms283fg05, backlight_gpio
   - suspend/resume bugfix; lp855x_bl
   - devm_gpiod_get_optional() API fixup; pwm_bl
   - error handling fixup; backlight"

* tag 'backlight-for-linus-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: Change the return type of backlight_update_status() to int
  backlight: pwm_bl: Simplify usage of devm_gpiod_get_optional
  backlight: lp855x: Don't clear level on suspend/blank
  backlight: Allow compile test of GPIO consumers if !GPIOLIB
  video: backlight: da9052: Constify platform_device_id
  gpio-backlight: Discover driver during boot time

drivers/video/backlight/Kconfig

@@ -36,14 +36,16 @@ config LCD_CORGI
 
 config LCD_L4F00242T03
 	tristate "Epson L4F00242T03 LCD"
-	depends on SPI_MASTER && GPIOLIB
+	depends on SPI_MASTER
+	depends on GPIOLIB || COMPILE_TEST
 	help
 	  SPI driver for Epson L4F00242T03. This provides basic support
 	  for init and powering the LCD up/down through a sysfs interface.
 
 config LCD_LMS283GF05
 	tristate "Samsung LMS283GF05 LCD"
-	depends on SPI_MASTER && GPIOLIB
+	depends on SPI_MASTER
+	depends on GPIOLIB || COMPILE_TEST
 	help
 	  SPI driver for Samsung LMS283GF05. This provides basic support
 	  for powering the LCD up/down through a sysfs interface.
@@ -434,7 +436,7 @@ config BACKLIGHT_AS3711
 
 config BACKLIGHT_GPIO
 	tristate "Generic GPIO based Backlight Driver"
-	depends on GPIOLIB
+	depends on GPIOLIB || COMPILE_TEST
 	help
 	  If you have a LCD backlight adjustable by GPIO, say Y to enable
 	  this driver.

drivers/video/backlight/da9052_bl.c

@@ -152,7 +152,7 @@ static int da9052_backlight_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static struct platform_device_id da9052_wled_ids[] = {
+static const struct platform_device_id da9052_wled_ids[] = {
 	{
 		.name		= "da9052-wled1",
 		.driver_data	= DA9052_TYPE_WLED1,

drivers/video/backlight/gpio_backlight.c

@@ -146,6 +146,8 @@ static struct of_device_id gpio_backlight_of_match[] = {
 	{ .compatible = "gpio-backlight" },
 	{ /* sentinel */ }
 };
+
+MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
 #endif
 
 static struct platform_driver gpio_backlight_driver = {

drivers/video/backlight/lp855x_bl.c

@@ -257,21 +257,15 @@ static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 static int lp855x_bl_update_status(struct backlight_device *bl)
 {
 	struct lp855x *lp = bl_get_data(bl);
+	int brightness = bl->props.brightness;
 
 	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
-		bl->props.brightness = 0;
+		brightness = 0;
 
-	if (lp->mode == PWM_BASED) {
+	if (lp->mode == PWM_BASED)
-		int br = bl->props.brightness;
+		lp855x_pwm_ctrl(lp, brightness, bl->props.max_brightness);
-		int max_br = bl->props.max_brightness;
+	else if (lp->mode == REGISTER_BASED)
-
+		lp855x_write_byte(lp, lp->cfg->reg_brightness, (u8)brightness);
-		lp855x_pwm_ctrl(lp, br, max_br);
-
-	} else if (lp->mode == REGISTER_BASED) {
-		u8 val = bl->props.brightness;
-
-		lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
-	}
 
 	return 0;
 }

drivers/video/backlight/pwm_bl.c

@@ -241,7 +241,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	pb->dev = &pdev->dev;
 	pb->enabled = false;
 
-	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable");
+	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
+						  GPIOD_OUT_HIGH);
 	if (IS_ERR(pb->enable_gpio)) {
 		ret = PTR_ERR(pb->enable_gpio);
 		goto err_alloc;
@@ -263,9 +264,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		pb->enable_gpio = gpio_to_desc(data->enable_gpio);
 	}
 
-	if (pb->enable_gpio)
-		gpiod_direction_output(pb->enable_gpio, 1);
-
 	pb->power_supply = devm_regulator_get(&pdev->dev, "power");
 	if (IS_ERR(pb->power_supply)) {
 		ret = PTR_ERR(pb->power_supply);

include/linux/backlight.h

@@ -117,12 +117,16 @@ struct backlight_device {
 	int use_count;
 };
 
-static inline void backlight_update_status(struct backlight_device *bd)
+static inline int backlight_update_status(struct backlight_device *bd)
 {
+	int ret = -ENOENT;
+
 	mutex_lock(&bd->update_lock);
 	if (bd->ops && bd->ops->update_status)
-		bd->ops->update_status(bd);
+		ret = bd->ops->update_status(bd);
 	mutex_unlock(&bd->update_lock);
+
+	return ret;
 }
 
 extern struct backlight_device *backlight_device_register(const char *name,