ACPI video: support _BQC/_BCL/_BCM methods that use index values

The input/output of _BQC/_BCL/_BCM control methods should be represented
by a number between 0 and 100, and can be thought of as a percentage.
But some buggy _BQC/_BCL/_BCM methods use the index values instead.
http://bugzilla.kernel.org/show_bug.cgi?id=12302
http://bugzilla.kernel.org/show_bug.cgi?id=12249
http://bugzilla.kernel.org/show_bug.cgi?id=12037

Add the functionality to support such kind of BIOSes in ACPI video driver.

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>

1 files changed, 70 insertions, 21 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index dc84970ce1e9..1f1625c51003 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -171,6 +171,9 @@ struct acpi_video_device_cap {
 struct acpi_video_brightness_flags {
         u8 _BCL_no_ac_battery_levels:1; /* no AC/Battery levels in _BCL */
         u8 _BCL_reversed:1;             /* _BCL package is in a reversed order*/
+        u8 _BCL_use_index:1;            /* levels in _BCL are index values */
+        u8 _BCM_use_index:1;            /* input of _BCM is an index value */
+        u8 _BQC_use_index:1;            /* _BQC returns an index value */
 };
 
 struct acpi_video_device_brightness {
@@ -505,7 +508,8 @@ acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
         device->brightness->curr = level;
         for (state = 2; state < device->brightness->count; state++)
                 if (level == device->brightness->levels[state]) {
-                        device->backlight->props.brightness = state - 2;
+                        if (device->backlight)
+                                device->backlight->props.brightness = state - 2;
                         return 0;
                 }
 
@@ -523,6 +527,13 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
                 status = acpi_evaluate_integer(device->dev->handle, "_BQC",
                                                 NULL, level);
                 if (ACPI_SUCCESS(status)) {
+                        if (device->brightness->flags._BQC_use_index) {
+                                if (device->brightness->flags._BCL_reversed)
+                                        *level = device->brightness->count
+                                                                 - 3 - (*level);
+                                *level = device->brightness->levels[*level + 2];
+
+                        }
                         device->brightness->curr = *level;
                         return 0;
                 } else {
@@ -689,8 +700,10 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 {
         union acpi_object *obj = NULL;
         int i, max_level = 0, count = 0, level_ac_battery = 0;
+        unsigned long long level, level_old;
         union acpi_object *o;
         struct acpi_video_device_brightness *br = NULL;
+        int result = -EINVAL;
 
         if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
@@ -704,13 +717,16 @@ acpi_video_init_brightness(struct acpi_video_device *device)
         br = kzalloc(sizeof(*br), GFP_KERNEL);
         if (!br) {
                 printk(KERN_ERR "can't allocate memory\n");
+                result = -ENOMEM;
                 goto out;
         }
 
         br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
                                 GFP_KERNEL);
-        if (!br->levels)
+        if (!br->levels) {
+                result = -ENOMEM;
                 goto out_free;
+        }
 
         for (i = 0; i < obj->package.count; i++) {
                 o = (union acpi_object *)&obj->package.elements[i];
@@ -756,10 +772,55 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 
         br->count = count;
         device->brightness = br;
+
+        /* Check the input/output of _BQC/_BCL/_BCM */
+        if ((max_level < 100) && (max_level <= (count - 2)))
+                br->flags._BCL_use_index = 1;
+
+        /*
+         * _BCM is always consistent with _BCL,
+         * at least for all the laptops we have ever seen.
+         */
+        br->flags._BCM_use_index = br->flags._BCL_use_index;
+
+        /* _BQC uses INDEX while _BCL uses VALUE in some laptops */
+        br->curr = max_level;
+        result = acpi_video_device_lcd_get_level_current(device, &level_old);
+        if (result)
+                goto out_free_levels;
+
+        result = acpi_video_device_lcd_set_level(device, br->curr);
+        if (result)
+                goto out_free_levels;
+
+        result = acpi_video_device_lcd_get_level_current(device, &level);
+        if (result)
+                goto out_free_levels;
+
+        if ((level != level_old) && !br->flags._BCM_use_index) {
+                /* Note:
+                 * This piece of code does not work correctly if the current
+                 * brightness levels is 0.
+                 * But I guess boxes that boot with such a dark screen are rare
+                 * and no more code is needed to cover this specifial case.
+                 */
+
+                if (level_ac_battery != 2) {
+                        /*
+                         * For now, we don't support the _BCL like this:
+                         * 16, 15, 0, 1, 2, 3, ..., 14, 15, 16
+                         * because we may mess up the index returned by _BQC.
+                         * Plus: we have not got a box like this.
+                         */
+                        ACPI_ERROR((AE_INFO, "_BCL not supported\n"));
+                }
+                br->flags._BQC_use_index = 1;
+        }
+
         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                           "found %d brightness levels\n", count - 2));
         kfree(obj);
-        return max_level;
+        return result;
 
 out_free_levels:
         kfree(br->levels);
@@ -768,7 +829,7 @@ out_free:
 out:
         device->brightness = NULL;
         kfree(obj);
-        return 0;
+        return result;
 }
 
 /*
@@ -785,7 +846,6 @@ out:
 static void acpi_video_device_find_cap(struct acpi_video_device *device)
 {
         acpi_handle h_dummy1;
-        u32 max_level = 0;
 
 
         memset(&device->cap, 0, sizeof(device->cap));
@@ -814,13 +874,14 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
                 device->cap._DSS = 1;
         }
 
-        if (acpi_video_backlight_support())
-                max_level = acpi_video_init_brightness(device);
-
-        if (device->cap._BCL && device->cap._BCM && max_level > 0) {
+        if (acpi_video_backlight_support()) {
                 int result;
                 static int count = 0;
                 char *name;
+
+                result = acpi_video_init_brightness(device);
+                if (result)
+                        return;
                 name = kzalloc(MAX_NAME_LEN, GFP_KERNEL);
                 if (!name)
                         return;
@@ -829,18 +890,6 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
                 device->backlight = backlight_device_register(name,
                         NULL, device, &acpi_backlight_ops);
                 device->backlight->props.max_brightness = device->brightness->count-3;
-                /*
-                 * If there exists the _BQC object, the _BQC object will be
-                 * called to get the current backlight brightness. Otherwise
-                 * the brightness will be set to the maximum.
-                 */
-                if (device->cap._BQC)
-                        device->backlight->props.brightness =
-                                acpi_video_get_brightness(device->backlight);
-                else
-                        device->backlight->props.brightness =
-                                device->backlight->props.max_brightness;
-                backlight_update_status(device->backlight);
                 kfree(name);
 
                 device->cdev = thermal_cooling_device_register("LCD",