ACPI video: Be more liberal in validating _BQC behaviour

Right now, if _BQC returns a value we don't understand we immediately
invalidate it. Change this behaviour so we only invalidate it if it
continues to give an invalid answer after we've already set a brightness.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index b765790b32b..ea314a2ecd1 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -327,7 +327,7 @@ static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
                         int level);
 static int acpi_video_device_lcd_get_level_current(
                         struct acpi_video_device *device,
-                        unsigned long long *level);
+                        unsigned long long *level, int init);
 static int acpi_video_get_next_level(struct acpi_video_device *device,
                                      u32 level_current, u32 event);
 static int acpi_video_switch_brightness(struct acpi_video_device *device,
@@ -345,7 +345,7 @@ static int acpi_video_get_brightness(struct backlight_device *bd)
         struct acpi_video_device *vd =
                 (struct acpi_video_device *)bl_get_data(bd);
 
-        if (acpi_video_device_lcd_get_level_current(vd, &cur_level))
+        if (acpi_video_device_lcd_get_level_current(vd, &cur_level, 0))
                 return -EINVAL;
         for (i = 2; i < vd->brightness->count; i++) {
                 if (vd->brightness->levels[i] == cur_level)
@@ -414,7 +414,7 @@ static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsig
         unsigned long long level;
         int offset;
 
-        if (acpi_video_device_lcd_get_level_current(video, &level))
+        if (acpi_video_device_lcd_get_level_current(video, &level, 0))
                 return -EINVAL;
         for (offset = 2; offset < video->brightness->count; offset++)
                 if (level == video->brightness->levels[offset]) {
@@ -609,7 +609,7 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
 
 static int
 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
-                                        unsigned long long *level)
+                                        unsigned long long *level, int init)
 {
         acpi_status status = AE_OK;
         int i;
@@ -633,10 +633,16 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
                                         device->brightness->curr = *level;
                                         return 0;
                         }
-                        /* BQC returned an invalid level. Stop using it.  */
-                        ACPI_WARNING((AE_INFO, "%s returned an invalid level",
-                                                buf));
-                        device->cap._BQC = device->cap._BCQ = 0;
+                        if (!init) {
+                                /*
+                                 * BQC returned an invalid level.
+                                 * Stop using it.
+                                 */
+                                ACPI_WARNING((AE_INFO,
+                                              "%s returned an invalid level",
+                                              buf));
+                                device->cap._BQC = device->cap._BCQ = 0;
+                        }
                 } else {
                         /* Fixme:
                          * should we return an error or ignore this failure?
@@ -892,7 +898,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
         if (!device->cap._BQC)
                 goto set_level;
 
-        result = acpi_video_device_lcd_get_level_current(device, &level_old);
+        result = acpi_video_device_lcd_get_level_current(device, &level_old, 1);
         if (result)
                 goto out_free_levels;
 
@@ -903,7 +909,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
         if (result)
                 goto out_free_levels;
 
-        result = acpi_video_device_lcd_get_level_current(device, &level);
+        result = acpi_video_device_lcd_get_level_current(device, &level, 0);
         if (result)
                 goto out_free_levels;
 
@@ -1996,7 +2002,7 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event)
                 goto out;
 
         result = acpi_video_device_lcd_get_level_current(device,
-                                                         &level_current);
+                                                         &level_current, 0);
         if (result)
                 goto out;