Signed-off-by: Alban Bedel <alban.be...@avionic-design.de>
---
.../bindings/video/backlight/pwm-backlight.txt | 1 +
drivers/video/backlight/pwm_bl.c | 22 ++++++++++++++-----
include/linux/pwm_backlight.h | 1 +
3 files changed, 18 insertions(+), 6 deletions(-)
diff --git
a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..3a40539 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,6 +14,7 @@ Required properties:
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
"pwms" property (see PWM binding[0])
+ - active-low: boolean indicating that the backlight use active low logic
[0]: Documentation/devicetree/bindings/pwm/pwm.txt
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 995f016..109c703 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -25,6 +25,7 @@ struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
unsigned int period;
+ unsigned int active_low;
unsigned int lth_brightness;
unsigned int *levels;
int (*notify)(struct device *,
@@ -40,6 +41,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
int brightness = bl->props.brightness;
int max = bl->props.max_brightness;
+ int duty_cycle;
if (bl->props.power != FB_BLANK_UNBLANK)
brightness = 0;
@@ -51,11 +53,8 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
brightness = pb->notify(pb->dev, brightness);
if (brightness == 0) {
- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ duty_cycle = 0;
} else {
- int duty_cycle;
-
if (pb->levels) {
duty_cycle = pb->levels[brightness];
max = pb->levels[max];
@@ -65,10 +64,17 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
duty_cycle = pb->lth_brightness +
(duty_cycle * (pb->period - pb->lth_brightness) / max);
- pwm_config(pb->pwm, duty_cycle, pb->period);
- pwm_enable(pb->pwm);
}
+ if (pb->active_low)
+ duty_cycle = pb->period - duty_cycle;
+
+ pwm_config(pb->pwm, duty_cycle, pb->period);
+ if (duty_cycle == 0)
+ pwm_disable(pb->pwm);
+ else
+ pwm_enable(pb->pwm);
+
if (pb->notify_after)
pb->notify_after(pb->dev, brightness);
@@ -145,6 +151,9 @@ static int pwm_backlight_parse_dt(struct device *dev,
data->max_brightness--;
}
+ /* Is the backlight low active? */
+ data->active_low = of_property_read_bool(node, "active-low");
+
/*
* TODO: Most users of this driver use a number of GPIOs to control
* backlight power. Support for specifying these needs to be
@@ -237,6 +246,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->period = pwm_get_period(pb->pwm);
pb->lth_brightness = data->lth_brightness * (pb->period / max);
+ pb->active_low = data->active_low;
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h
index 56f4a86..52b19d9 100644
--- a/include/linux/pwm_backlight.h
+++ b/include/linux/pwm_backlight.h
@@ -12,6 +12,7 @@ struct platform_pwm_backlight_data {
unsigned int dft_brightness;
unsigned int lth_brightness;
unsigned int pwm_period_ns;
+ unsigned int active_low;
unsigned int *levels;
int (*init)(struct device *dev);
int (*notify)(struct device *dev, int brightness);
--
1.7.0.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
