[PATCH] backlight: pwm_bl: Do not make the regulator mandatory

[fabio.estevam@freescale.com (Fabio Estevam)]

Commit 22ceeee1 (pwm-backlight: Add power supply support) caused breakage on 
boards that do not define the backlight regulator on their dts files.

Instead of making the backlight regulator mandatory, treat it as optional 
instead, so that we do not have breakage.

This avoids the need for adding a dummy regulator on every dts file that uses 
the pwm-backlight.

Tested on a mx6qsabresd.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
 .../devicetree/bindings/video/backlight/pwm-backlight.txt |  2 +-
 drivers/video/backlight/pwm_bl.c                          | 15 +++++++--------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 764db86..ed3dc3c 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -10,13 +10,13 @@ Required properties:
       last value in the array represents a 100% duty cycle (brightest).
   - default-brightness-level: the default brightness level (index into the
       array defined by the "brightness-levels" property)
-  - power-supply: regulator for supply voltage
 
 Optional properties:
   - pwm-names: a list of names for the PWM devices specified in the
                "pwms" property (see PWM binding[0])
   - enable-gpios: contains a single GPIO specifier for the GPIO which enables
                   and disables the backlight (see GPIO binding[1])
+  - power-supply: regulator for supply voltage
 
 [0]: Documentation/devicetree/bindings/pwm/pwm.txt
 [1]: Documentation/devicetree/bindings/gpio/gpio.txt
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index fb80d68..fb3008c 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -50,9 +50,11 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
 	if (pb->enabled)
 		return;
 
-	err = regulator_enable(pb->power_supply);
-	if (err < 0)
-		dev_err(pb->dev, "failed to enable power supply\n");
+	if (!IS_ERR(pb->power_supply)) {
+		err = regulator_enable(pb->power_supply);
+		if (err < 0)
+			dev_err(pb->dev, "failed to enable power supply\n");
+	}
 
 	if (gpio_is_valid(pb->enable_gpio)) {
 		if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
@@ -80,7 +82,8 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
 			gpio_set_value(pb->enable_gpio, 0);
 	}
 
-	regulator_disable(pb->power_supply);
+	if (!IS_ERR(pb->power_supply))
+		regulator_disable(pb->power_supply);
 	pb->enabled = false;
 }
 
@@ -283,10 +286,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	}
 
 	pb->power_supply = devm_regulator_get(&pdev->dev, "power");
-	if (IS_ERR(pb->power_supply)) {
-		ret = PTR_ERR(pb->power_supply);
-		goto err_gpio;
-	}
 
 	pb->pwm = devm_pwm_get(&pdev->dev, NULL);
 	if (IS_ERR(pb->pwm)) {
-- 
1.8.1.2