[PATCH v2 04/11] video: backlight-pwm: make power-supply and enable-gpio optional

[Johannes Schneider]

From: Thomas Haemmerle <thomas.haemmerle at leica-geosystems.com>

Boards often omit power-supply (rail is always-on) or use enable-gpios
without a discrete supply.  The driver returned -ENODEV when either was
missing, blocking display init.

Switch to regulator_get_optional() so a missing power-supply property
surfaces as -ENODEV (instead of a silent NULL the IS_ERR check never
catches), and handle that case by leaving ->power = NULL.
regulator_enable() / regulator_disable() are already NULL-safe, no
extra guards needed at the call sites.

While here, fix the GPIO descriptor name: gpiod_get_optional() appends
"-gpios" itself, so the previous "enable-gpios" looked for a non-existent
"enable-gpios-gpios" property and never resolved the enable GPIO.  Use
"enable" with GPIOD_ASIS so the boot-time pin state is preserved.

Use dev_errp_probe() for the PWM lookup so the underlying error and
deferred-probe path are propagated correctly; drop an unused 'ret' in
of_backlight_find().

Fixes: 4c7238df6866 ("video: backlight-pwm: switch to gpiod functions")
Signed-off-by: Thomas Haemmerle <thomas.haemmerle at leica-geosystems.com>
---
 drivers/video/backlight-pwm.c | 16 ++++++++--------
 drivers/video/backlight.c     |  2 +-
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/video/backlight-pwm.c b/drivers/video/backlight-pwm.c
index d3c81114e0..14fad55637 100644
--- a/drivers/video/backlight-pwm.c
+++ b/drivers/video/backlight-pwm.c
@@ -148,7 +148,7 @@ static int pwm_backlight_parse_dt(struct device *dev,
 		pwm_backlight->backlight.brightness_max = pwm_backlight->scale;
 	}
 
-	pwm_backlight->enable_gpio = gpiod_get_optional(dev, "enable-gpios", 0);
+	pwm_backlight->enable_gpio = gpiod_get_optional(dev, "enable", GPIOD_ASIS);
 
 	return 0;
 }
@@ -160,10 +160,8 @@ static int backlight_pwm_of_probe(struct device *dev)
 	struct pwm_device *pwm;
 
 	pwm = of_pwm_request(dev->of_node, NULL);
-	if (IS_ERR(pwm)) {
-		dev_err(dev, "Cannot find PWM device\n");
-		return PTR_ERR(pwm);
-	}
+	if (IS_ERR(pwm))
+		return dev_errp_probe(dev, pwm, "Cannot find PWM device\n");
 
 	pwm_backlight = xzalloc(sizeof(*pwm_backlight));
 	pwm_backlight->pwm = pwm;
@@ -173,10 +171,12 @@ static int backlight_pwm_of_probe(struct device *dev)
 	if (ret)
 		return ret;
 
-	pwm_backlight->power = regulator_get(dev, "power");
+	pwm_backlight->power = regulator_get_optional(dev, "power");
 	if (IS_ERR(pwm_backlight->power)) {
-		dev_err(dev, "Cannot find regulator\n");
-		return PTR_ERR(pwm_backlight->power);
+		if (PTR_ERR(pwm_backlight->power) != -ENODEV)
+			return dev_errp_probe(dev, pwm_backlight->power,
+					      "power supply\n");
+		pwm_backlight->power = NULL;
 	}
 
 	pwm_backlight->backlight.slew_time_ms = 100;
diff --git a/drivers/video/backlight.c b/drivers/video/backlight.c
index 6d8146ee5a..066742fe28 100644
--- a/drivers/video/backlight.c
+++ b/drivers/video/backlight.c
@@ -95,7 +95,7 @@ struct backlight_device *of_backlight_find(struct device_node *node)
 {
 	struct backlight_device *bl;
 
-	of_device_ensure_probed(node);
+	(void)of_device_ensure_probed(node);
 
 	class_for_each_container_of_device(&backlight_class, bl, dev)
 		if (bl->node == node)
-- 
2.43.0