asus-wmi: fix and clean backlight code

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

1 files changed, 29 insertions, 15 deletions

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index fd5b08eecf1e..adf7b05c9aef 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -765,9 +765,8 @@ static int read_backlight_power(struct asus_wmi *asus)
         return ret ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
 }
 
-static int read_brightness(struct backlight_device *bd)
+static int read_brightness_max(struct asus_wmi *asus)
 {
-        struct asus_wmi *asus = bl_get_data(bd);
         u32 retval;
         int err;
 
@@ -776,6 +775,25 @@ static int read_brightness(struct backlight_device *bd)
         if (err < 0)
                 return err;
 
+        retval = retval & ASUS_WMI_DSTS_MAX_BRIGTH_MASK;
+        retval >>= 8;
+
+        if (!retval)
+                return -ENODEV;
+
+        return retval;
+}
+
+static int read_brightness(struct backlight_device *bd)
+{
+        struct asus_wmi *asus = bl_get_data(bd);
+        u32 retval, err;
+
+        err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_BRIGHTNESS, &retval);
+
+        if (err < 0)
+                return err;
+
         return retval & ASUS_WMI_DSTS_BRIGHTNESS_MASK;
 }
 
@@ -799,7 +817,7 @@ static int update_bl_status(struct backlight_device *bd)
                 err = asus_wmi_set_devstate(ASUS_WMI_DEVID_BACKLIGHT,
                                             ctrl_param, NULL);
         }
-        return 0;
+        return err;
 }
 
 static const struct backlight_ops asus_wmi_bl_ops = {
@@ -832,23 +850,19 @@ static int asus_wmi_backlight_init(struct asus_wmi *asus)
         int max;
         int power;
 
-        max = asus_wmi_get_devstate_bits(asus, ASUS_WMI_DEVID_BRIGHTNESS,
-                                         ASUS_WMI_DSTS_MAX_BRIGTH_MASK);
-        power = read_backlight_power(asus);
+        max = read_brightness_max(asus);
 
-        if (max < 0 && power < 0) {
-                /* Try to keep the original error */
-                if (max == -ENODEV && power == -ENODEV)
-                        return -ENODEV;
-                if (max != -ENODEV)
-                        return max;
-                else
-                        return power;
-        }
         if (max == -ENODEV)
                 max = 0;
+        else if (max < 0)
+                return max;
+
+        power = read_backlight_power(asus);
+
         if (power == -ENODEV)
                 power = FB_BLANK_UNBLANK;
+        else if (power < 0)
+                return power;
 
         memset(&props, 0, sizeof(struct backlight_properties));
         props.max_brightness = max;