ACPI video: check the return value of acpi_video_device_lcd_get_level_current

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Matthew Garrett <mjg59@srcf.ucam.org>
Acked-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index bb5ed05..f0e6eb5 100644 (file)
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -294,7 +294,7 @@ static int acpi_video_device_lcd_get_level_current(
                        unsigned long long *level);
 static int acpi_video_get_next_level(struct acpi_video_device *device,
                                     u32 level_current, u32 event);
-static void acpi_video_switch_brightness(struct acpi_video_device *device,
+static int acpi_video_switch_brightness(struct acpi_video_device *device,
                                         int event);
 static int acpi_video_device_get_state(struct acpi_video_device *device,
                            unsigned long long *state);
@@ -308,7 +308,9 @@ static int acpi_video_get_brightness(struct backlight_device *bd)
        int i;
        struct acpi_video_device *vd =
                (struct acpi_video_device *)bl_get_data(bd);
-       acpi_video_device_lcd_get_level_current(vd, &cur_level);
+
+       if (acpi_video_device_lcd_get_level_current(vd, &cur_level))
+               return -EINVAL;
        for (i = 2; i < vd->brightness->count; i++) {
                if (vd->brightness->levels[i] == cur_level)
                        /* The first two entries are special - see page 575
@@ -373,7 +375,8 @@ static int video_get_cur_state(struct thermal_cooling_device *cdev, char *buf)
        unsigned long long level;
        int state;
 
-       acpi_video_device_lcd_get_level_current(video, &level);
+       if (acpi_video_device_lcd_get_level_current(video, &level))
+               return -EINVAL;
        for (state = 2; state < video->brightness->count; state++)
                if (level == video->brightness->levels[state])
                        return sprintf(buf, "%d\n",
@@ -502,11 +505,29 @@ static int
 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
                                        unsigned long long *level)
 {
-       if (device->cap._BQC)
-               return acpi_evaluate_integer(device->dev->handle, "_BQC", NULL,
-                                            level);
+       acpi_status status = AE_OK;
+
+       if (device->cap._BQC) {
+               status = acpi_evaluate_integer(device->dev->handle, "_BQC",
+                                               NULL, level);
+               if (ACPI_SUCCESS(status)) {
+                       device->brightness->curr = *level;
+                       return 0;
+               } else {
+                       /* Fixme:
+                        * should we return an error or ignore this failure?
+                        * dev->brightness->curr is a cached value which stores
+                        * the correct current backlight level in most cases.
+                        * ACPI video backlight still works w/ buggy _BQC.
+                        * http://bugzilla.kernel.org/show_bug.cgi?id=12233
+                        */
+                       ACPI_WARNING((AE_INFO, "Evaluating _BQC failed"));
+                       device->cap._BQC = 0;
+               }
+       }
+
        *level = device->brightness->curr;
-       return AE_OK;
+       return 0;
 }
 
 static int
@@ -1749,15 +1770,29 @@ acpi_video_get_next_level(struct acpi_video_device *device,
        }
 }
 
-static void
+static int
 acpi_video_switch_brightness(struct acpi_video_device *device, int event)
 {
        unsigned long long level_current, level_next;
+       int result = -EINVAL;
+
        if (!device->brightness)
-               return;
-       acpi_video_device_lcd_get_level_current(device, &level_current);
+               goto out;
+
+       result = acpi_video_device_lcd_get_level_current(device,
+                                                        &level_current);
+       if (result)
+               goto out;
+
        level_next = acpi_video_get_next_level(device, level_current, event);
+
        acpi_video_device_lcd_set_level(device, level_next);
+
+out:
+       if (result)
+               printk(KERN_ERR PREFIX "Failed to switch the brightness\n");
+
+       return result;
 }
 
 static int