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>
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 32e96e3..f77a7b0 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -45,21 +45,11 @@
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);
-
err = regulator_enable(pb->power_supply);
if (err < 0)
dev_err(pb->dev, "failed to enable power supply\n");
@@ -94,10 +84,24 @@
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 ||
@@ -107,9 +111,11 @@
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)