diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 334b1db1bd7c..27597c576eff 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -29,12 +29,15 @@ static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
 
 static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
 {
-	int rc = -ENXIO, power;
+	int rc = -ENXIO;
 	char *endp;
 	struct backlight_device *bd = to_backlight_device(cdev);
+	int power = simple_strtoul(buf, &endp, 0);
+	size_t size = endp - buf;
 
-	power = simple_strtoul(buf, &endp, 0);
-	if (*endp && !isspace(*endp))
+	if (*endp && isspace(*endp))
+		size++;
+	if (size != count)
 		return -EINVAL;
 
 	down(&bd->sem);
@@ -65,12 +68,15 @@ static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
 
 static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
 {
-	int rc = -ENXIO, brightness;
+	int rc = -ENXIO;
 	char *endp;
 	struct backlight_device *bd = to_backlight_device(cdev);
+	int brightness = simple_strtoul(buf, &endp, 0);
+	size_t size = endp - buf;
 
-	brightness = simple_strtoul(buf, &endp, 0);
-	if (*endp && !isspace(*endp))
+	if (*endp && isspace(*endp))
+		size++;
+	if (size != count)
 		return -EINVAL;
 
 	down(&bd->sem);
diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index 86908a60c630..bc8ab005a3fb 100644
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -31,12 +31,15 @@ static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
 
 static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
 {
-	int rc, power;
+	int rc = -ENXIO;
 	char *endp;
 	struct lcd_device *ld = to_lcd_device(cdev);
+	int power = simple_strtoul(buf, &endp, 0);
+	size_t size = endp - buf;
 
-	power = simple_strtoul(buf, &endp, 0);
-	if (*endp && !isspace(*endp))
+	if (*endp && isspace(*endp))
+		size++;
+	if (size != count)
 		return -EINVAL;
 
 	down(&ld->sem);
@@ -44,8 +47,7 @@ static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_
 		pr_debug("lcd: set power to %d\n", power);
 		ld->props->set_power(ld, power);
 		rc = count;
-	} else
-		rc = -ENXIO;
+	}
 	up(&ld->sem);
 
 	return rc;
@@ -53,14 +55,12 @@ static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_
 
 static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
 {
-	int rc;
+	int rc = -ENXIO;
 	struct lcd_device *ld = to_lcd_device(cdev);
 
 	down(&ld->sem);
 	if (likely(ld->props && ld->props->get_contrast))
 		rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
-	else
-		rc = -ENXIO;
 	up(&ld->sem);
 
 	return rc;
@@ -68,12 +68,15 @@ static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
 
 static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
 {
-	int rc, contrast;
+	int rc = -ENXIO;
 	char *endp;
 	struct lcd_device *ld = to_lcd_device(cdev);
+	int contrast = simple_strtoul(buf, &endp, 0);
+	size_t size = endp - buf;
 
-	contrast = simple_strtoul(buf, &endp, 0);
-	if (*endp && !isspace(*endp))
+	if (*endp && isspace(*endp))
+		size++;
+	if (size != count)
 		return -EINVAL;
 
 	down(&ld->sem);
@@ -81,8 +84,7 @@ static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, si
 		pr_debug("lcd: set contrast to %d\n", contrast);
 		ld->props->set_contrast(ld, contrast);
 		rc = count;
-	} else
-		rc = -ENXIO;
+	}
 	up(&ld->sem);
 
 	return rc;
@@ -90,14 +92,12 @@ static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, si
 
 static ssize_t lcd_show_max_contrast(struct class_device *cdev, char *buf)
 {
-	int rc;
+	int rc = -ENXIO;
 	struct lcd_device *ld = to_lcd_device(cdev);
 
 	down(&ld->sem);
 	if (likely(ld->props))
 		rc = sprintf(buf, "%d\n", ld->props->max_contrast);
-	else
-		rc = -ENXIO;
 	up(&ld->sem);
 
 	return rc;