1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 550443518891..b8f38ec6eb18 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -25,8 +25,10 @@ struct pwm_bl_data {
         struct pwm_device       *pwm;
         struct device           *dev;
         unsigned int            period;
+        unsigned int            lth_brightness;
         int                     (*notify)(struct device *,
                                           int brightness);
+        int                     (*check_fb)(struct device *, struct fb_info *);
 };
 
 static int pwm_backlight_update_status(struct backlight_device *bl)
@@ -48,7 +50,9 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
                 pwm_config(pb->pwm, 0, pb->period);
                 pwm_disable(pb->pwm);
         } else {
-                pwm_config(pb->pwm, brightness * pb->period / max, pb->period);
+                brightness = pb->lth_brightness +
+                        (brightness * (pb->period - pb->lth_brightness) / max);
+                pwm_config(pb->pwm, brightness, pb->period);
                 pwm_enable(pb->pwm);
         }
         return 0;
@@ -59,9 +63,18 @@ static int pwm_backlight_get_brightness(struct backlight_device *bl)
         return bl->props.brightness;
 }
 
+static int pwm_backlight_check_fb(struct backlight_device *bl,
+                                  struct fb_info *info)
+{
+        struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+        return !pb->check_fb || pb->check_fb(pb->dev, info);
+}
+
 static const struct backlight_ops pwm_backlight_ops = {
         .update_status  = pwm_backlight_update_status,
         .get_brightness = pwm_backlight_get_brightness,
+        .check_fb       = pwm_backlight_check_fb,
 };
 
 static int pwm_backlight_probe(struct platform_device *pdev)
@@ -92,6 +105,9 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 
         pb->period = data->pwm_period_ns;
         pb->notify = data->notify;
+        pb->check_fb = data->check_fb;
+        pb->lth_brightness = data->lth_brightness *
+                (data->pwm_period_ns / data->max_brightness);
         pb->dev = &pdev->dev;
 
         pb->pwm = pwm_request(data->pwm_id, "backlight");
@@ -103,6 +119,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
                 dev_dbg(&pdev->dev, "got pwm for backlight\n");
 
         memset(&props, 0, sizeof(struct backlight_properties));
+        props.type = BACKLIGHT_RAW;
         props.max_brightness = data->max_brightness;
         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
                                        &pwm_backlight_ops, &props);