pwm-backlight: Fix brightness adjustment

Split adjustment of the brightness (by changing the PWM duty cycle) from
the power on sequence. This fixes an issue where the brightness can no
longer be updated once the backlight has been enabled.

Reported-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Conflicts:
	drivers/video/backlight/pwm_bl.c

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 4323edaf253b3fdff2f080cf0388b9b6cdcc7de7..e5a0e7dc48aba5380ed7c23e21ad94c5681642a3 100644 (file)
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -43,21 +43,11 @@ struct pwm_bl_data {
 
 static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
 {
-       unsigned int lth = pb->lth_brightness;
        int duty_cycle, err;
 
        if (pb->enabled)
                return;
 
-       if (pb->levels)
-               duty_cycle = pb->levels[brightness];
-       else
-               duty_cycle = brightness;
-
-       duty_cycle = (duty_cycle * (pb->period - lth) / pb->scale) + lth;
-
-       pwm_config(pb->pwm, duty_cycle, pb->period);
-
        if (gpio_is_valid(pb->enable_gpio)) {
                if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
                        gpio_set_value(pb->enable_gpio, 0);
@@ -87,10 +77,24 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
        pb->enabled = false;
 }
 
+static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
+{
+       unsigned int lth = pb->lth_brightness;
+       int duty_cycle;
+
+       if (pb->levels)
+               duty_cycle = pb->levels[brightness];
+       else
+               duty_cycle = brightness;
+
+       return (duty_cycle * (pb->period - lth) / pb->scale) + lth;
+}
+
 static int pwm_backlight_update_status(struct backlight_device *bl)
 {
        struct pwm_bl_data *pb = bl_get_data(bl);
        int brightness = bl->props.brightness;
+       int duty_cycle;
 
        if (bl->props.power != FB_BLANK_UNBLANK ||
            bl->props.fb_blank != FB_BLANK_UNBLANK ||
@@ -100,9 +104,11 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
        if (pb->notify)
                brightness = pb->notify(pb->dev, brightness);
 
-       if (brightness > 0)
+       if (brightness > 0) {
+               duty_cycle = compute_duty_cycle(pb, brightness);
+               pwm_config(pb->pwm, duty_cycle, pb->period);
                pwm_backlight_power_on(pb, brightness);
-       else
+       } else
                pwm_backlight_power_off(pb);
 
        if (pb->notify_after)