ACPI / video: get rid of magic numbers and use enum instead

The first two items in the _BCL method response are special:

  - Level when machine has full power
  - Level when machine is on batteries
  - .... actual supported levels go there ....

So this commits adds an enum and uses its descriptive elements
throughout the code, instead of magic numbers.

Signed-off-by: Dmitry Frank <mail@dmitryfrank.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index d00bc0ef87a67a0517a2406cc6149d922d0feea6..9a607af971e78213e301fc98e09ffbf87c50f8ff 100644 (file)
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -88,6 +88,18 @@ static int acpi_video_bus_remove(struct acpi_device *device);
 static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
 void acpi_video_detect_exit(void);
 
+/*
+ * Indices in the _BCL method response: the first two items are special,
+ * the rest are all supported levels.
+ *
+ * See page 575 of the ACPI spec 3.0
+ */
+enum acpi_video_level_idx {
+       ACPI_VIDEO_AC_LEVEL,            /* level when machine has full power */
+       ACPI_VIDEO_BATTERY_LEVEL,       /* level when machine is on batteries */
+       ACPI_VIDEO_FIRST_LEVEL,         /* actual supported levels begin here */
+};
+
 static const struct acpi_device_id video_device_ids[] = {
        {ACPI_VIDEO_HID, 0},
        {"", 0},
@@ -217,20 +229,16 @@ static int acpi_video_get_brightness(struct backlight_device *bd)
 
        if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
                return -EINVAL;
-       for (i = 2; i < vd->brightness->count; i++) {
+       for (i = ACPI_VIDEO_FIRST_LEVEL; i < vd->brightness->count; i++) {
                if (vd->brightness->levels[i] == cur_level)
-                       /*
-                        * The first two entries are special - see page 575
-                        * of the ACPI spec 3.0
-                        */
-                       return i - 2;
+                       return i - ACPI_VIDEO_FIRST_LEVEL;
        }
        return 0;
 }
 
 static int acpi_video_set_brightness(struct backlight_device *bd)
 {
-       int request_level = bd->props.brightness + 2;
+       int request_level = bd->props.brightness + ACPI_VIDEO_FIRST_LEVEL;
        struct acpi_video_device *vd = bl_get_data(bd);
 
        cancel_delayed_work(&vd->switch_brightness_work);
@@ -244,18 +252,18 @@ static const struct backlight_ops acpi_backlight_ops = {
 };
 
 /* thermal cooling device callbacks */
-static int video_get_max_state(struct thermal_cooling_device *cooling_dev, unsigned
-                              long *state)
+static int video_get_max_state(struct thermal_cooling_device *cooling_dev,
+                              unsigned long *state)
 {
        struct acpi_device *device = cooling_dev->devdata;
        struct acpi_video_device *video = acpi_driver_data(device);
 
-       *state = video->brightness->count - 3;
+       *state = video->brightness->count - ACPI_VIDEO_FIRST_LEVEL - 1;
        return 0;
 }
 
-static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsigned
-                              long *state)
+static int video_get_cur_state(struct thermal_cooling_device *cooling_dev,
+                              unsigned long *state)
 {
        struct acpi_device *device = cooling_dev->devdata;
        struct acpi_video_device *video = acpi_driver_data(device);
@@ -264,7 +272,8 @@ static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsig
 
        if (acpi_video_device_lcd_get_level_current(video, &level, false))
                return -EINVAL;
-       for (offset = 2; offset < video->brightness->count; offset++)
+       for (offset = ACPI_VIDEO_FIRST_LEVEL; offset < video->brightness->count;
+            offset++)
                if (level == video->brightness->levels[offset]) {
                        *state = video->brightness->count - offset - 1;
                        return 0;
@@ -280,7 +289,7 @@ video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long st
        struct acpi_video_device *video = acpi_driver_data(device);
        int level;
 
-       if (state >= video->brightness->count - 2)
+       if (state >= video->brightness->count - ACPI_VIDEO_FIRST_LEVEL)
                return -EINVAL;
 
        state = video->brightness->count - state;
@@ -345,10 +354,12 @@ 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++)
+       for (state = ACPI_VIDEO_FIRST_LEVEL; state < device->brightness->count;
+            state++)
                if (level == device->brightness->levels[state]) {
                        if (device->backlight)
-                               device->backlight->props.brightness = state - 2;
+                               device->backlight->props.brightness =
+                                       state - ACPI_VIDEO_FIRST_LEVEL;
                        return 0;
                }
 
@@ -530,14 +541,16 @@ acpi_video_bqc_value_to_level(struct acpi_video_device *device,
 
        if (device->brightness->flags._BQC_use_index) {
                /*
-                * _BQC returns an index that doesn't account for
-                * the first 2 items with special meaning, so we need
-                * to compensate for that by offsetting ourselves
+                * _BQC returns an index that doesn't account for the first 2
+                * items with special meaning (see enum acpi_video_level_idx),
+                * so we need to compensate for that by offsetting ourselves
                 */
                if (device->brightness->flags._BCL_reversed)
-                       bqc_value = device->brightness->count - 3 - bqc_value;
+                       bqc_value = device->brightness->count -
+                               ACPI_VIDEO_FIRST_LEVEL - 1 - bqc_value;
 
-               level = device->brightness->levels[bqc_value + 2];
+               level = device->brightness->levels[bqc_value +
+                                                  ACPI_VIDEO_FIRST_LEVEL];
        } else {
                level = bqc_value;
        }
@@ -571,7 +584,8 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 
                        *level = acpi_video_bqc_value_to_level(device, *level);
 
-                       for (i = 2; i < device->brightness->count; i++)
+                       for (i = ACPI_VIDEO_FIRST_LEVEL;
+                            i < device->brightness->count; i++)
                                if (device->brightness->levels[i] == *level) {
                                        device->brightness->curr = *level;
                                        return 0;
@@ -716,7 +730,9 @@ static int acpi_video_bqc_quirk(struct acpi_video_device *device,
         * Some systems always report current brightness level as maximum
         * through _BQC, we need to test another value for them.
         */
-       test_level = current_level == max_level ? br->levels[3] : max_level;
+       test_level = current_level == max_level
+               ? br->levels[ACPI_VIDEO_FIRST_LEVEL + 1]
+               : max_level;
 
        result = acpi_video_device_lcd_set_level(device, test_level);
        if (result)
@@ -730,8 +746,8 @@ static int acpi_video_bqc_quirk(struct acpi_video_device *device,
                /* buggy _BQC found, need to find out if it uses index */
                if (level < br->count) {
                        if (br->flags._BCL_reversed)
-                               level = br->count - 3 - level;
-                       if (br->levels[level + 2] == test_level)
+                               level = br->count - ACPI_VIDEO_FIRST_LEVEL - 1 - level;
+                       if (br->levels[level + ACPI_VIDEO_FIRST_LEVEL] == test_level)
                                br->flags._BQC_use_index = 1;
                }
 
@@ -761,7 +777,7 @@ int acpi_video_get_levels(struct acpi_device *device,
                goto out;
        }
 
-       if (obj->package.count < 2) {
+       if (obj->package.count < ACPI_VIDEO_FIRST_LEVEL) {
                result = -EINVAL;
                goto out;
        }
@@ -773,8 +789,8 @@ int acpi_video_get_levels(struct acpi_device *device,
                goto out;
        }
 
-       br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
-                               GFP_KERNEL);
+       br->levels = kmalloc((obj->package.count + ACPI_VIDEO_FIRST_LEVEL) *
+                            sizeof(*br->levels), GFP_KERNEL);
        if (!br->levels) {
                result = -ENOMEM;
                goto out_free;
@@ -788,7 +804,8 @@ int acpi_video_get_levels(struct acpi_device *device,
                }
                value = (u32) o->integer.value;
                /* Skip duplicate entries */
-               if (count > 2 && br->levels[count - 1] == value)
+               if (count > ACPI_VIDEO_FIRST_LEVEL
+                   && br->levels[count - 1] == value)
                        continue;
 
                br->levels[count] = value;
@@ -804,27 +821,30 @@ int acpi_video_get_levels(struct acpi_device *device,
         * In this case, the first two elements in _BCL packages
         * are also supported brightness levels that OS should take care of.
         */
-       for (i = 2; i < count; i++) {
-               if (br->levels[i] == br->levels[0])
+       for (i = ACPI_VIDEO_FIRST_LEVEL; i < count; i++) {
+               if (br->levels[i] == br->levels[ACPI_VIDEO_AC_LEVEL])
                        level_ac_battery++;
-               if (br->levels[i] == br->levels[1])
+               if (br->levels[i] == br->levels[ACPI_VIDEO_BATTERY_LEVEL])
                        level_ac_battery++;
        }
 
-       if (level_ac_battery < 2) {
-               level_ac_battery = 2 - level_ac_battery;
+       if (level_ac_battery < ACPI_VIDEO_FIRST_LEVEL) {
+               level_ac_battery = ACPI_VIDEO_FIRST_LEVEL - level_ac_battery;
                br->flags._BCL_no_ac_battery_levels = 1;
-               for (i = (count - 1 + level_ac_battery); i >= 2; i--)
+               for (i = (count - 1 + level_ac_battery);
+                    i >= ACPI_VIDEO_FIRST_LEVEL; i--)
                        br->levels[i] = br->levels[i - level_ac_battery];
                count += level_ac_battery;
-       } else if (level_ac_battery > 2)
+       } else if (level_ac_battery > ACPI_VIDEO_FIRST_LEVEL)
                ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package"));
 
        /* Check if the _BCL package is in a reversed order */
-       if (max_level == br->levels[2]) {
+       if (max_level == br->levels[ACPI_VIDEO_FIRST_LEVEL]) {
                br->flags._BCL_reversed = 1;
-               sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
-                       acpi_video_cmp_level, NULL);
+               sort(&br->levels[ACPI_VIDEO_FIRST_LEVEL],
+                    count - ACPI_VIDEO_FIRST_LEVEL,
+                    sizeof(br->levels[ACPI_VIDEO_FIRST_LEVEL]),
+                    acpi_video_cmp_level, NULL);
        } else if (max_level != br->levels[count - 1])
                ACPI_ERROR((AE_INFO,
                            "Found unordered _BCL package"));
@@ -894,7 +914,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
         * level_old is invalid (no matter whether it's a level
         * or an index). Set the backlight to max_level in this case.
         */
-       for (i = 2; i < br->count; i++)
+       for (i = ACPI_VIDEO_FIRST_LEVEL; i < br->count; i++)
                if (level == br->levels[i])
                        break;
        if (i == br->count || !level)
@@ -906,7 +926,8 @@ set_level:
                goto out_free_levels;
 
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-                         "found %d brightness levels\n", br->count - 2));
+                         "found %d brightness levels\n",
+                         br->count - ACPI_VIDEO_FIRST_LEVEL));
        return 0;
 
 out_free_levels:
@@ -1297,7 +1318,7 @@ acpi_video_get_next_level(struct acpi_video_device *device,
        max = max_below = 0;
        min = min_above = 255;
        /* Find closest level to level_current */
-       for (i = 2; i < device->brightness->count; i++) {
+       for (i = ACPI_VIDEO_FIRST_LEVEL; i < device->brightness->count; i++) {
                l = device->brightness->levels[i];
                if (abs(l - level_current) < abs(delta)) {
                        delta = l - level_current;
@@ -1307,7 +1328,7 @@ acpi_video_get_next_level(struct acpi_video_device *device,
        }
        /* Ajust level_current to closest available level */
        level_current += delta;
-       for (i = 2; i < device->brightness->count; i++) {
+       for (i = ACPI_VIDEO_FIRST_LEVEL; i < device->brightness->count; i++) {
                l = device->brightness->levels[i];
                if (l < min)
                        min = l;
@@ -1680,7 +1701,8 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
 
        memset(&props, 0, sizeof(struct backlight_properties));
        props.type = BACKLIGHT_FIRMWARE;
-       props.max_brightness = device->brightness->count - 3;
+       props.max_brightness =
+               device->brightness->count - ACPI_VIDEO_FIRST_LEVEL - 1;
        device->backlight = backlight_device_register(name,
                                                      parent,
                                                      device,