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Subject[PATCH 09/10] pwm-backlight: Use an optional power supply
Date
Many backlights require a power supply to work properly. This commit
uses a power-supply regulator, if available, to power up and power down
the panel.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
.../bindings/video/backlight/pwm-backlight.txt | 2 ++
drivers/video/backlight/pwm_bl.c | 21 +++++++++++++++++++++
2 files changed, 23 insertions(+)

diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 052eb03..3898f26 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -15,6 +15,7 @@ Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
"pwms" property (see PWM binding[0])
- enable-gpios: a list of GPIOs to enable and disable the backlight
+ - power-supply: regulator for supply voltage

[0]: Documentation/devicetree/bindings/pwm/pwm.txt

@@ -28,4 +29,5 @@ Example:
default-brightness-level = <6>;

enable-gpios = <&gpio 58 0>;
+ power-supply = <&vdd_bl_reg>;
};
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 506810c..a2b3876 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -21,6 +21,7 @@
#include <linux/err.h>
#include <linux/pwm.h>
#include <linux/pwm_backlight.h>
+#include <linux/regulator/consumer.h>
#include <linux/slab.h>

struct pwm_bl_data {
@@ -29,6 +30,7 @@ struct pwm_bl_data {
unsigned int period;
unsigned int lth_brightness;
unsigned int *levels;
+ struct regulator *power_supply;
int enable_gpio;
unsigned long enable_gpio_flags;
int (*notify)(struct device *,
@@ -56,6 +58,12 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness,

pwm_config(pb->pwm, duty_cycle, pb->period);

+ if (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)
gpio_set_value(pb->enable_gpio, 0);
@@ -76,6 +84,9 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
else
gpio_set_value(pb->enable_gpio, 0);
}
+
+ if (pb->power_supply)
+ regulator_disable(pb->power_supply);
}

static int pwm_backlight_update_status(struct backlight_device *bl)
@@ -253,6 +264,16 @@ static int pwm_backlight_probe(struct platform_device *pdev)
}
}

+ pb->power_supply = devm_regulator_get_optional(&pdev->dev, "power");
+ if (IS_ERR(pb->power_supply)) {
+ if (PTR_ERR(pb->power_supply) != -ENODEV) {
+ ret = PTR_ERR(pb->power_supply);
+ goto err_gpio;
+ }
+
+ pb->power_supply = NULL;
+ }
+
pb->pwm = devm_pwm_get(&pdev->dev, NULL);
if (IS_ERR(pb->pwm)) {
dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
--
1.8.4


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