Merge tag 'backlight-next-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight

Pull backlight updates from Lee Jones:
 "Core Frameworks
   - Obtain scale type through sysfs

  New Functionality:
   - Provide Device Tree functionality in rave-sp-backlight
   - Calculate if scale type is (non-)linear in pwm_bl

  Fix-ups:
   - Simplify code in lm3630a_bl
   - Trivial rename/whitespace/typo fixes in lms283gf05
   - Remove superfluous NULL check in tosa_lcd
   - Fix power state initialisation in gpio_backlight
   - List supported file in MAINTAINERS

  Bug Fixes:
   - Kconfig - default to not building unless requested in
     {LED,BACKLIGHT}_CLASS_DEVICE"

* tag 'backlight-next-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: pwm_bl: Set scale type for brightness curves specified in the DT
  backlight: pwm_bl: Set scale type for CIE 1931 curves
  backlight: Expose brightness curve type through sysfs
  MAINTAINERS: Add entry for stable backlight sysfs ABI documentation
  backlight: gpio-backlight: Correct initial power state handling
  video: backlight: tosa_lcd: drop check because i2c_unregister_device() is NULL safe
  video: backlight: Drop default m for {LCD,BACKLIGHT_CLASS_DEVICE}
  backlight: lms283gf05: Fix a typo in the description passed to 'devm_gpio_request_one()'
  backlight: lm3630a: Switch to use fwnode_property_count_uXX()
  backlight: rave-sp: Leave initial state and register with correct device

1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index e84f3087e29f..18e053e4716c 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -59,13 +59,11 @@ static int gpio_backlight_probe_dt(struct platform_device *pdev,
 				   struct gpio_backlight *gbl)
 {
 	struct device *dev = &pdev->dev;
-	enum gpiod_flags flags;
 	int ret;
 
 	gbl->def_value = device_property_read_bool(dev, "default-on");
-	flags = gbl->def_value ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
 
-	gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
+	gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
 	if (IS_ERR(gbl->gpiod)) {
 		ret = PTR_ERR(gbl->gpiod);
 
@@ -79,6 +77,22 @@ static int gpio_backlight_probe_dt(struct platform_device *pdev,
 	return 0;
 }
 
+static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl)
+{
+	struct device_node *node = gbl->dev->of_node;
+
+	/* Not booted with device tree or no phandle link to the node */
+	if (!node || !node->phandle)
+		return gbl->def_value ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
+
+	/* if the enable GPIO is disabled, do not enable the backlight */
+	if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
+		return FB_BLANK_POWERDOWN;
+
+	return FB_BLANK_UNBLANK;
+}
+
+
 static int gpio_backlight_probe(struct platform_device *pdev)
 {
 	struct gpio_backlight_platform_data *pdata =
@@ -136,7 +150,9 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 		return PTR_ERR(bl);
 	}
 
-	bl->props.brightness = gbl->def_value;
+	bl->props.power = gpio_backlight_initial_power_state(gbl);
+	bl->props.brightness = 1;
+
 	backlight_update_status(bl);
 
 	platform_set_drvdata(pdev, bl);