Merge lp:~sforshee/powerd/backlight-settings into lp:powerd

[Seth Forshee]

* Add dbus interfaces to allow getting brightness parameters and changing brightness settings
* Add powerd-cli support for these new dbus interfaces
* Change backlight code to use Android HAL for changing brightness, making it compatible with more devices
* Disable autobrightness on startup until user setting is supplied
* Fix build warning
* Eliminate short delay before changing screen brightness when going from a dim or off state to bright with autobrightness enabled (LP: #1221672)

* Add dbus interfaces to allow getting brightness parameters and changing brightness settings
* Add powerd-cli support for these new dbus interfaces
* Change backlight code to use Android HAL for changing brightness, making it compatible with more devices
* Disable autobrightness on startup until user setting is supplied
* Fix build warning
* Eliminate short delay before changing screen brightness when going from a dim or off state to bright with autobrightness enabled (LP: #1221672)

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:110
http://jenkins.qa.ubuntu.com/job/powerd-ci/119/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/powerd-saucy-armhf-ci/73
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review: Approve (continuous-integration)

[PS Jenkins bot (ps-jenkins)]

FAILED: Continuous integration, rev:110
http://jenkins.qa.ubuntu.com/job/powerd-ci/120/
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review: Needs Fixing (continuous-integration)

[lp:~sforshee/powerd/backlight-settings]

111. By Seth Forshee on 2013-09-26

Merge with master

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:111
http://jenkins.qa.ubuntu.com/job/powerd-ci/121/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/powerd-saucy-armhf-ci/75
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review: Approve (continuous-integration)

[lp:~sforshee/powerd/backlight-settings]

112. By Seth Forshee on 2013-09-27

Merge with trunk

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:112
http://jenkins.qa.ubuntu.com/job/powerd-ci/122/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/powerd-saucy-armhf-ci/76
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review: Approve (continuous-integration)

[lp:~sforshee/powerd/backlight-settings]

113. By Seth Forshee on 2014-01-14

Merge with trunk

Also fix up some dependencies and hybris backlight integration
due to external changes since this code was written.

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:113
http://jenkins.qa.ubuntu.com/job/powerd-ci/135/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/powerd-trusty-armhf-ci/5
        deb: http://jenkins.qa.ubuntu.com/job/powerd-trusty-armhf-ci/5/artifact/work/output/*zip*/output.zip

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review: Approve (continuous-integration)

[Michael Frey (mfrey)]

tested works great. Now need to reflect new API in settings.

review: Approve

=== modified file 'CMakeLists.txt'
--- CMakeLists.txt	2014-01-03 15:07:52 +0000
+++ CMakeLists.txt	2014-01-14 03:16:31 +0000
@@ -26,7 +26,6 @@
 pkg_check_modules(GLIB glib-2.0)
 pkg_check_modules(GIO gio-2.0)
 pkg_check_modules(GIO-UNIX gio-unix-2.0)
-pkg_check_modules(LIBUDEV libudev)
 pkg_check_modules(UPOWER_GLIB upower-glib)
 pkg_check_modules(UUID uuid)
 
@@ -67,7 +66,6 @@
   ${GLIB_LIBRARY_DIRS}
   ${GIO_LIBRARY_DIRS}
   ${GIO-UNIX_LIBRARY_DIRS}
-  ${LIBUDEV_LIBRARY_DIRS}
   ${UPOWER_GLIB_LIBRARY_DIRS}
   ${UUID_LIBRARY_DIRS}
 )
@@ -77,7 +75,6 @@
   ${GLIB_INCLUDE_DIRS}
   ${GIO_INCLUDE_DIRS}
   ${GIO-UNIX_INCLUDE_DIRS}
-  ${LIBUDEV_INCLUDE_DIRS}
   ${UPOWER_GLIB_INCLUDE_DIRS}
   ${UUID_INCLUDE_DIRS}
   ${PROJECT_SOURCE_DIR}/libsuspend
@@ -119,7 +116,6 @@
   "-lubuntu_application_api"
   "-landroid-properties"
   "-lhardware"
-  ${LIBUDEV_LIBRARIES}
   ${UPOWER_GLIB_LIBRARIES}
   ${UUID_LIBRARIES}
 )

=== modified file 'cli/powerd-cli.c'
--- cli/powerd-cli.c	2013-08-12 14:32:56 +0000
+++ cli/powerd-cli.c	2014-01-14 03:16:31 +0000
@@ -21,6 +21,8 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
+#include <limits.h>
 #include <unistd.h>
 #include <inttypes.h>
 #include <sys/types.h>
@@ -895,6 +897,65 @@
 }
 
 static void
+setUserAutobrightness(gboolean enable)
+{
+    GVariant *ret = NULL;
+    GError *error = NULL;
+    
+    ret = g_dbus_proxy_call_sync(powerd_proxy,
+            "userAutobrightnessEnable",
+            g_variant_new("(b)", enable),
+            G_DBUS_CALL_FLAGS_NONE,
+            -1, NULL, &error);
+    if (!ret) {
+        cli_warn("userAutobrightnessEnable failed: %s", error->message);
+        g_error_free(error);
+    } else {
+        g_variant_unref(ret);
+    }
+}
+
+static gboolean
+getBrightnessParams(int *min, int *max, int *dflt, gboolean *ab_supported)
+{
+    GVariant *ret = NULL;
+    GError *error = NULL;
+
+    ret = g_dbus_proxy_call_sync(powerd_proxy,
+            "getBrightnessParams",
+            NULL,
+            G_DBUS_CALL_FLAGS_NONE,
+            -1, NULL, &error);
+    if (!ret) {
+        cli_warn("getBrightnessParams failed: %s", error->message);
+        g_error_free(error);
+        return FALSE;
+    }
+
+    g_variant_get(ret, "((iiib))", min, max, dflt, ab_supported);
+    g_variant_unref(ret);
+    return TRUE;
+}
+
+static void setUserBrightness(int brightness)
+{
+    GVariant *ret = NULL;
+    GError *error = NULL;
+    
+    ret = g_dbus_proxy_call_sync(powerd_proxy,
+            "setUserBrightness",
+            g_variant_new("(i)", brightness),
+            G_DBUS_CALL_FLAGS_NONE,
+            -1, NULL, &error);
+    if (!ret) {
+        cli_warn("setUserBrightness failed: %s", error->message);
+        g_error_free(error);
+    } else {
+        g_variant_unref(ret);
+    }
+}
+
+static void
 usage(const char *progname)
 {
     printf("\n\n%s Options:\n",progname);
@@ -903,6 +964,9 @@
     printf("active-nc - same as active, but relies on powerd to cleanup\n"\
             "\tthe request. This is only for testing and will immediately"\
             "exit, causing the request to be dropped.\n");
+    printf("autobrightness <enable|disable> - enable or disable autobrightness\n");
+    printf("brightness <brightness> - set user screen brightness\n");
+    printf("brightness-params - get brightness parameters (min, max, etc.)\n");
     printf("clear-sys <cookie> - clear a System state request given a cookie\n");
     printf("clear-disp <cookie> - clear a Display state request given a cookie\n");
     printf("client-test - test powerd registration / ack API\n");
@@ -955,7 +1019,10 @@
        (strcmp(argv[1],"help")) &&
        (strcmp(argv[1],"clear-disp")) &&
        (strcmp(argv[1],"clear-sys")) &&
-       (strcmp(argv[1],"client-test"))) {
+       (strcmp(argv[1],"client-test")) &&
+       (strcmp(argv[1], "autobrightness")) &&
+       (strcmp(argv[1], "brightness-params")) &&
+       (strcmp(argv[1], "brightness"))) {
         fprintf(stderr,"Invalid option %s\n",argv[1]);
         usage(argv[0]);
         return -1;
@@ -1108,6 +1175,47 @@
     }
     else if (!strcmp(argv[1], "client-test")) {
         powerd_cli_client_test(powerd_proxy);
+    } else if (!strcmp(argv[1], "autobrightness")) {
+        gboolean enable;
+        if (argc != 3) {
+            usage(argv[0]);
+            exit(-1);
+        }
+        if (!strcmp(argv[2], "enable")) {
+            enable = TRUE;
+        } else if (!strcmp(argv[2], "disable")) {
+            enable = FALSE;
+        } else {
+            fprintf(stderr, "Invalid autobrightness state\n");
+            usage(argv[0]);
+            exit(-1);
+        }
+        setUserAutobrightness(enable);
+    } else if (!strcmp(argv[1], "brightness-params")) {
+        int min, max, dflt, ab;
+        if (getBrightnessParams(&min, &max, &dflt, &ab)) {
+            printf("Minimum Brightness: %d\n"
+                   "Maximum Brightness: %d\n"
+                   "Default Brightness: %d\n"
+                   "Autobrightness:     %ssupported\n",
+                   min, max, dflt, ab ? "" : "not ");
+        }
+    } else if (!strcmp(argv[1], "brightness")) {
+        long brightness;
+        char *endp;
+        if (argc != 3) {
+            usage(argv[0]);
+            exit(-1);
+        }
+        errno = 0;
+        brightness = strtol(argv[2], &endp, 10);
+        if (errno == ERANGE || *endp != '\0' ||
+            brightness < 0 || brightness > INT_MAX) {
+            fprintf(stderr, "Invalid brightness %s\n", argv[2]);
+            usage(argv[0]);
+            exit(-1);
+        }
+        setUserBrightness((int)brightness);
     }
     return 0;
 }

=== modified file 'data/com.canonical.powerd.xml'
--- data/com.canonical.powerd.xml	2013-08-12 02:46:09 +0000
+++ data/com.canonical.powerd.xml	2014-01-14 03:16:31 +0000
@@ -27,6 +27,10 @@
       <arg type="u" name="flags" direction="in" />
     </method>
 
+    <method name="clearDisplayState">
+      <arg type="s" name="cookie" direction="in" />
+    </method>
+
     <method name="registerClient">
         <arg type="s" name="name" direction="in" />
     </method>
@@ -39,8 +43,19 @@
         <arg type="i" name="state" direction="in" />
     </method>
 
-    <method name="clearDisplayState">
-      <arg type="s" name="cookie" direction="in" />
+    <!-- User settings -->
+    <method name="userAutobrightnessEnable">
+        <arg type="b" name="enable" direction="in" />
+    </method>
+
+    <method name="getBrightnessParams">
+        <!-- Returns min, max, and default brighness and whether or not
+             autobrightness is supported, in that order -->
+        <arg type="(iiib)" name="params" direction="out" />
+    </method>
+
+    <method name="setUserBrightness">
+        <arg type="i" name="brightness" direction="in" />
     </method>
 
     <!-- for debug/testing -->

=== modified file 'data/device_configs/config-default.xml'
--- data/device_configs/config-default.xml	2013-08-29 21:22:33 +0000
+++ data/device_configs/config-default.xml	2014-01-14 03:16:31 +0000
@@ -54,6 +54,18 @@
     <integer-array name="config_autoBrightnessLevels">
     </integer-array>
 
+    <!-- Minimum screen brightness setting allowed by the power manager.
+         The user is forbidden from setting the brightness below this level. -->
+    <integer name="config_screenBrightnessSettingMinimum">10</integer>
+
+    <!-- Maximum screen brightness allowed by the power manager.
+         The user is forbidden from setting the brightness above this level. -->
+    <integer name="config_screenBrightnessSettingMaximum">255</integer>
+
+    <!-- Default screen brightness setting.
+         Must be in the range specified by minimum and maximum. -->
+    <integer name="config_screenBrightnessSettingDefault">102</integer>
+
     <!-- Screen brightness used to dim the screen when the user activity
          timeout expires.  May be less than the minimum allowed brightness setting
          that can be set by the user. -->

=== modified file 'data/device_configs/config-mako.xml'
--- data/device_configs/config-mako.xml	2013-08-29 21:22:33 +0000
+++ data/device_configs/config-mako.xml	2014-01-14 03:16:31 +0000
@@ -69,6 +69,14 @@
     <!-- Minimum screen brightness allowed by the power manager. -->
     <integer name="config_screenBrightnessDim">1</integer>
 
+    <!-- Default screen brightness setting.
+         Must be in the range specified by minimum and maximum. -->
+    <integer name="config_screenBrightnessSettingDefault">87</integer>
+
+    <!-- Minimum screen brightness setting allowed by the power manager.
+         The user is forbidden from setting the brightness below this level. -->
+    <integer name="config_screenBrightnessSettingMinimum">1</integer>
+
     <!-- Shutdown if the battery temperature exceeds (this value * 0.1) Celsius. -->
     <integer name="config_shutdownBatteryTemperature">600</integer>
 

=== modified file 'debian/changelog'
--- debian/changelog	2014-01-08 06:17:09 +0000
+++ debian/changelog	2014-01-14 03:16:31 +0000
@@ -1,3 +1,18 @@
+powerd (0.13+14.04.20140108.1-0ubuntu2) UNRELEASED; urgency=low
+
+  * Add dbus interfaces to allow getting brightness parameters and
+    changing brightness settings
+  * Add powerd-cli support for these new dbus interfaces
+  * Change backlight code to use Android HAL for changing brightness,
+    making it compatible with more devices
+  * Disable autobrightness on startup until user setting is supplied
+  * Fix build warning
+  * Eliminate short delay before changing screen brightness when going
+    from a dim or off state to bright with autobrightness enabled
+    (LP: #1221672)
+
+ -- Seth Forshee <[e-mail]>  Mon, 13 Jan 2014 15:59:44 -0600
+
 powerd (0.13+14.04.20140108.1-0ubuntu1) trusty; urgency=low
 
   [ Ricardo Salveti de Araujo ]

=== modified file 'debian/control'
--- debian/control	2013-12-06 22:11:52 +0000
+++ debian/control	2014-01-14 03:16:31 +0000
@@ -7,7 +7,6 @@
                libglib2.0-dev,
                android-headers (>= 4.2.2),
                libhybris-dev (>= 0.1.0+git20131206+0cdd7f2-0ubuntu1),
-               libudev-dev,
                python,
                libandroid-properties-dev,
                libplatform-api1-dev,

=== modified file 'src/autobrightness.c'
--- src/autobrightness.c	2013-09-04 14:41:22 +0000
+++ src/autobrightness.c	2014-01-14 03:16:31 +0000
@@ -274,6 +274,11 @@
     }
 }
 
+gboolean powerd_autobrightness_available(void)
+{
+    return ab_supported;
+}
+
 int powerd_autobrightness_init(void)
 {
     GValue v = G_VALUE_INIT;

=== modified file 'src/backlight.c'
--- src/backlight.c	2013-07-02 15:50:42 +0000
+++ src/backlight.c	2014-01-14 03:16:31 +0000
@@ -21,344 +21,150 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <errno.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <libudev.h>
 #include <glib.h>
-#include <glib-unix.h>
+#include <glib-object.h>
+#include <android/hardware/hardware.h>
+#include <android/hardware/lights.h>
 
 #include "powerd-internal.h"
+#include "device-config.h"
 #include "log.h"
 
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
-
-struct udev *udev;
-struct udev_monitor *udev_mon;
-guint udev_mon_source_id;
-
-enum bl_type {
-    BL_TYPE_FIRMWARE,
-    BL_TYPE_PLATFORM,
-    BL_TYPE_RAW,
-};
-
-static const char *bl_strs[] = {
-    [BL_TYPE_FIRMWARE]  = "firmware",
-    [BL_TYPE_PLATFORM]  = "platform",
-    [BL_TYPE_RAW]       = "raw",
-};
-
-struct bl_device {
-    struct udev_device *dev;
-    enum bl_type type;
-    int max_brightness;
-};
-
-struct bl_device *preferred_bl;
-GSList *bl_devices;
-
-static int bl_parse_type(const char *type_str)
-{
-    unsigned i;
-
-    for (i = 0; i < ARRAY_SIZE(bl_strs); i++) {
-        if (!strcmp(type_str, bl_strs[i]))
-            return i;
-    }
-    return -1;
-}
-
-static struct bl_device *new_backlight(struct udev_device *dev)
-{
-    struct bl_device *bl_dev;
-    int type;
-    long max_brightness;
-    const char *data;
-
-    powerd_debug("Processing backlight device %s",
-                 udev_device_get_syspath(dev));
-
-    data = udev_device_get_sysattr_value(dev, "type");
-    if (!data) {
-        powerd_error("Could not read backlight \"type\" attribute");
-        return NULL;
-    }
-    type = bl_parse_type(data);
-    if (type < 0) {
-        powerd_error("Invalid backlight type \"%s\"", data);
-        return NULL;
-    }
-
-    data = udev_device_get_sysattr_value(dev, "max_brightness");
-    if (!data) {
-        powerd_error("Could not read backlight \"max_brightness\" attribute");
-        return NULL;
-    }
-    errno = 0;
-    max_brightness = strtol(data, NULL, 10);
-    if (errno != 0) {
-        powerd_error("Invalid max_brightness \"%s\"", data);
-        return NULL;
-    }
-
-    bl_dev = malloc(sizeof(*bl_dev));
-    if (!bl_dev) {
-        powerd_error("Falied to allocate memory for backlight device: %s",
-                     strerror(errno));
-        return NULL;
-    }
-
-    udev_device_ref(dev);
-    bl_dev->dev = dev;
-    bl_dev->type = type;
-    bl_dev->max_brightness = (int)max_brightness;
-
-    return bl_dev;
-}
-
-static void free_backlight(struct bl_device *bl)
-{
-    udev_device_unref(bl->dev);
-    free(bl);
-}
-
-static gboolean remove_backlight(const char *path)
-{
-    GSList *item;
-    struct bl_device *bl;
-
-    for (item = bl_devices; item; item = g_slist_next(item)) {
-        bl = item->data;
-        if (!strcmp(path, udev_device_get_syspath(bl->dev))) {
-            bl_devices = g_slist_remove(bl_devices, bl);
-            free_backlight(bl);
-            return TRUE;
-        }
-    }
-
-    return FALSE;
-}
-
-static void update_preferred_backlight(void)
-{
-    GSList *item;
-    struct bl_device *bl;
-
-    preferred_bl = NULL;
-    for (item = bl_devices; item; item = g_slist_next(item)) {
-        bl = item->data;
-        if (!preferred_bl || bl->type < preferred_bl->type)
-            preferred_bl = bl;
-    }
-
-    if (preferred_bl)
-        powerd_info("Using backlight at %s",
-                    udev_device_get_syspath(preferred_bl->dev));
-    else
-        powerd_warn("No backlights present");
-}
-
-/* Returns number of backlight devices found */
-static int find_backlights(void)
-{
-    int found = 0;
-    struct udev_enumerate *enumerate;
-    struct udev_list_entry *devices, *dev_list_entry;
-
-    enumerate = udev_enumerate_new(udev);
-    udev_enumerate_add_match_subsystem(enumerate, "backlight");
-    udev_enumerate_scan_devices(enumerate);
-
-    devices = udev_enumerate_get_list_entry(enumerate);
-    udev_list_entry_foreach(dev_list_entry, devices) {
-        struct udev_device *dev;
-        const char *path;
-        struct bl_device *new_bl;
-
-        path = udev_list_entry_get_name(dev_list_entry);
-        dev = udev_device_new_from_syspath(udev, path);
-        new_bl = new_backlight(dev);
-        if (new_bl) {
-            bl_devices = g_slist_append(bl_devices, new_bl);
-            found++;
-        }
-        udev_device_unref(dev);
-    }
-
-    udev_enumerate_unref(enumerate);
-    return found;
-}
-
-static gboolean bl_monitor_handler(gint fd, GIOCondition cond, gpointer data)
-{
-    struct udev_device *dev;
-    const char *path, *action;
-    struct bl_device *new_bl;
-    gboolean update = FALSE;
-
-    dev = udev_monitor_receive_device(udev_mon);
-    if (dev) {
-        path = udev_device_get_syspath(dev);
-        action = udev_device_get_action(dev);
-        powerd_debug("Received action %s for %s", action, path);
-
-        if (!strcmp(action, "add")) {
-            new_bl = new_backlight(dev);
-            if (new_bl) {
-                bl_devices = g_slist_append(bl_devices, new_bl);
-                update = TRUE;
-            }
-        } else if (!strcmp(action, "remove")) {
-            update = remove_backlight(path);
-        }
-
-        udev_device_unref(dev);
-    }
-
-    if (update)
-        update_preferred_backlight();
-
-    return TRUE;
-}
-
-static int bl_monitor_init(void)
-{
-    int fd;
-
-    udev_mon = udev_monitor_new_from_netlink(udev, "udev");
-    if (!udev_mon)
-        return -ENODEV;
-
-    udev_monitor_filter_add_match_subsystem_devtype(udev_mon, "backlight", NULL);
-    udev_monitor_enable_receiving(udev_mon);
-    fd = udev_monitor_get_fd(udev_mon);
-    udev_mon_source_id = g_unix_fd_add(fd, G_IO_IN, bl_monitor_handler, NULL);
-    return 0;
-}
-
-static void bl_monitor_deinit(void)
-{
-    if (!udev_mon)
-        return;
-
-    g_source_remove(udev_mon_source_id);
-    udev_monitor_unref(udev_mon);
-    udev_mon = NULL;
-}
+struct light_device_t *light_dev;
+
+/*
+ * Defaults are Android default settings. They may not work if we
+ * can't read the per-device values, but they're as good as
+ * anything else.
+ */
+int min_user_brightness = 10;
+int max_brightness = 255;
+int default_brightness = 102;
+int dim_brightness = 10;
+int current_brightness = -1;
 
 int powerd_get_brightness(void)
 {
-    char path[128];
-    char data[32];
-    ssize_t ret;
-    int fd;
-
-    if (!udev || !preferred_bl)
-        return -ENODEV;
-
-    /*
-     * libudev interface returned cached values for attributes.
-     * When this is called we want to get the actual value from
-     * sysfs, so we must read it ourselves.
-     */
-    ret = snprintf(path, ARRAY_SIZE(path), "%s/%s",
-                   udev_device_get_syspath(preferred_bl->dev), "brightness");
-    if (ret >= ARRAY_SIZE(path)) {
-        powerd_warn("Buffer not big enough for path to brightness attribute");
-        return -EIO;
-    }
-
-    fd = open(path, O_RDONLY);
-    if (fd < 0) {
-        powerd_warn("Could not open %s", path);
-        return -errno;
-    }
-
-    ret = read(fd, data, ARRAY_SIZE(data) - 1);
-    if (ret < 0) {
-        powerd_warn("Failed to read brightness");
-        ret = errno;
-        goto error;
-    }
-    data[ret] = 0;
-
-    close(fd);
-    return atoi(data);
-
-error:
-    close(fd);
-    return (int)ret;
+    return current_brightness;
 }
 
 int powerd_get_max_brightness(void)
 {
-    if (!preferred_bl)
-        return -ENODEV;
-    return preferred_bl->max_brightness;
+    return max_brightness;
 }
 
 int powerd_set_brightness(int brightness)
 {
-    char buf[32];
+    struct light_state_t state;
+    int scaled_brightness;
     int ret;
 
-    if (!udev || !preferred_bl)
+    if (!light_dev)
         return -ENODEV;
-
-    ret = snprintf(buf, ARRAY_SIZE(buf), "%d", brightness);
-    if (ret >= ARRAY_SIZE(buf))
+    if (brightness < 0 || brightness > max_brightness)
         return -EINVAL;
-
-    return udev_device_set_sysattr_value(preferred_bl->dev, "brightness", buf);
+    if (brightness == current_brightness)
+        return 0;
+
+    /* Scale brightness to range of 0 to 255 */
+    scaled_brightness = (brightness * 255) / max_brightness;
+    if (scaled_brightness > 255)
+        scaled_brightness = 255;
+
+    state.flashMode = LIGHT_FLASH_NONE; 
+    state.brightnessMode = BRIGHTNESS_MODE_USER;
+    /* color is ARGB, docs specifiy that alpha should be 0xff,
+     * although it also instructs callers to ignore it. */
+    state.color = (int)((0xffU << 24) | (scaled_brightness << 16) |
+                        (scaled_brightness << 8) | scaled_brightness);
+
+    ret = light_dev->set_light(light_dev, &state);
+    if (!ret)
+        current_brightness = brightness;
+    return ret;
+}
+
+int powerd_set_user_brightness(int brightness)
+{
+    return powerd_set_brightness(brightness < min_user_brightness ?
+                                 min_user_brightness : brightness);
+}
+
+void powerd_dim_screen(void)
+{
+    powerd_set_brightness(dim_brightness);
 }
 
 int powerd_backlight_init(void)
 {
-    int count;
-
-    udev = udev_new();
-    if (!udev) {
-        powerd_error("udev_new() failed, backlight support is disabled");
-        return -ENODEV;
-    }
-
-    /*
-     * Start monitoring before scanning so we don't miss devices which
-     * might appear in the interim
-     */
-    bl_monitor_init();
-
-    count = find_backlights(); 
-    if (count)
-        update_preferred_backlight();
-    else
-        powerd_warn("No backlight devices found");
+    GValue v = G_VALUE_INIT;
+    const struct hw_module_t *hwmod = NULL;
+
+    if (!device_config_get("screenBrightnessDim", &v)) {
+        if (G_VALUE_HOLDS_UINT(&v))
+            dim_brightness = (int)g_value_get_uint(&v);
+        g_value_unset(&v);
+    }
+    if (!device_config_get("screenBrightnessSettingMinimum", &v)) {
+        if (G_VALUE_HOLDS_UINT(&v))
+            min_user_brightness = (int)g_value_get_uint(&v);
+        g_value_unset(&v);
+    }
+    if (!device_config_get("screenBrightnessSettingMaximum", &v)) {
+        if (G_VALUE_HOLDS_UINT(&v))
+            max_brightness = (int)g_value_get_uint(&v);
+        g_value_unset(&v);
+    }
+    if (!device_config_get("screenBrightnessSettingDefault", &v)) {
+        if (G_VALUE_HOLDS_UINT(&v))
+            default_brightness = (int)g_value_get_uint(&v);
+        g_value_unset(&v);
+    }
+
+    /* Sanity check default brightness value */
+    if (default_brightness < min_user_brightness)
+        default_brightness = min_user_brightness;
+    else if (default_brightness > max_brightness)
+        default_brightness = max_brightness;
+
+    if (hw_get_module(LIGHTS_HARDWARE_MODULE_ID, &hwmod)) {
+        powerd_warn("Could not get lights module");
+        return -ENODEV;
+    }
+    if (hwmod->methods->open(hwmod, LIGHT_ID_BACKLIGHT,
+                             (hw_device_t **)&light_dev)) {
+        powerd_warn("Could not open backlight, brightness adjustment will be disabled");
+        light_dev = NULL;
+        return -ENODEV;
+    }
+
+    /* XXX: May want to eliminate this when integration with shell
+     * is complete and just wait for it to apply user settings.
+     * Unfortunately the HAL provides no way for us to read the
+     * current brightness when we start. */
+    powerd_set_brightness(default_brightness);
 
     return 0;
 }
 
-static void bl_destroy(gpointer data)
-{
-    struct bl_device *bl = data;
-    free_backlight(bl);
-}
-
 void powerd_backlight_deinit(void)
 {
-    if (!udev)
-        return;
-
-    bl_monitor_deinit();
-    g_slist_free_full(bl_devices, bl_destroy);
-    udev_unref(udev);
-
-    bl_devices = NULL;
-    preferred_bl = NULL;
-    udev = NULL;
+    light_dev = NULL;
+}
+
+
+/** dbus interfaces **/
+
+gboolean handle_get_brightness_params(PowerdSource *obj,
+                                      GDBusMethodInvocation *invocation)
+{
+    gboolean ab_available = powerd_autobrightness_available();
+    g_dbus_method_invocation_return_value(invocation,
+                                          g_variant_new("((iiib))",
+                                                        min_user_brightness,
+                                                        max_brightness,
+                                                        default_brightness,
+                                                        ab_available));
+    return TRUE;
 }

=== modified file 'src/display.c'
--- src/display.c	2014-01-03 15:23:38 +0000
+++ src/display.c	2014-01-14 03:16:31 +0000
@@ -36,9 +36,18 @@
 
 #include "powerd.h"
 #include "powerd-internal.h"
-#include "device-config.h"
 #include "log.h"
 
+enum bl_state {
+    BL_OFF,
+    BL_DIM,
+    BL_BRIGHT,
+    BL_AUTO,
+
+    NUM_BL_STATES
+};
+static enum bl_state target_bl_state = BL_BRIGHT;
+
 /* Mir usage hint file path */
 #define MIR_HINT_PATH	"/home/phablet/.display-mir"
 
@@ -50,9 +59,8 @@
                          POWERD_DISPLAY_FLAG_DISABLE_AUTOBRIGHTNESS)
 #define AB_ENABLED      POWERD_DISPLAY_FLAG_BRIGHT
 
-static gint saved_brightness = 255;
-static gint target_brightness;
-static gint dim_brightness;
+static int user_brightness;
+static gboolean user_ab_enabled;
 static gboolean running_mir = FALSE;
 
 /* Assume screen is off to start; we will force it on */
@@ -91,9 +99,60 @@
 
 static gboolean ab_enabled(guint32 flags)
 {
+    if (!powerd_autobrightness_available())
+        return FALSE;
+    if (!user_ab_enabled)
+        return FALSE;
     return (flags & AB_ENABLED_MASK) == AB_ENABLED;
 }
 
+static void set_backlight(enum bl_state state)
+{
+    static enum bl_state current_state = BL_BRIGHT;
+    static int restore_brightness = 0;
+
+    if (state >= NUM_BL_STATES) {
+        powerd_warn("Unknown backlight state %d\n", state);
+        return;
+    }
+    if (state != BL_AUTO)
+        powerd_autobrightness_disable();
+
+    /*
+     * When we're enabling autobrightness it takes a second to
+     * settle on a brightness level after enabling. This delay
+     * becomes very noticible when going from the dim to bright
+     * state. To avoid this lag, save off the current brightness
+     * any time the state goes from BRIGHT or AUTO and restore
+     * it if transitioning back to AUTO.
+     */
+    if (current_state >= BL_BRIGHT && state < BL_BRIGHT)
+        restore_brightness = powerd_get_brightness();
+
+    switch (state) {
+    case BL_OFF:
+        powerd_set_brightness(0);
+        break;
+    case BL_DIM:
+        powerd_dim_screen();
+        break;
+    case BL_BRIGHT:
+        powerd_set_user_brightness(user_brightness);
+        break;
+    case BL_AUTO:
+        if (current_state < BL_BRIGHT && restore_brightness > 0)
+            powerd_set_brightness(restore_brightness);
+        powerd_autobrightness_enable();
+        break;
+    default:
+        /* default case is to satisfy static analysis tools, should
+         * never actually get here */
+        powerd_error("Unknwown backlight state %d\n", state);
+        return;
+    }
+    current_state = state;
+}
+
 gboolean display_set_power_mode(int display, char *power_mode)
 {
     GError *error = NULL;
@@ -146,13 +205,11 @@
     return TRUE;
 }
 
-static void turn_on_display(gboolean autobrightness) {
+static void turn_on_display(void)
+{
     powerd_debug("turning on display");
     display_set_power_mode(0, "on");
-    if (autobrightness)
-        powerd_autobrightness_enable();
-    else
-        powerd_set_brightness(target_brightness);
+    set_backlight(target_bl_state);
 }
 
 gboolean powerd_display_enabled(void)
@@ -160,49 +217,11 @@
     return actual_screen_state == POWERD_DISPLAY_STATE_ON;
 }
 
-static int get_target_brightness(gboolean request_bright, int hw_value)
-{
-    /*
-     * If not requesting bright, return the dim brightness, but never
-     * return something higher than the current "bright" brightness.
-     */
-    if (request_bright == FALSE)
-        return (saved_brightness < dim_brightness) ?
-               saved_brightness : dim_brightness;
-
-    /*
-     * If bright is requested and our current state is also bright,
-     * just return the current hardware value.
-     */
-    if ((internal_state.flags & POWERD_DISPLAY_FLAG_BRIGHT) && (hw_value > 0))
-        return hw_value;
-
-    /* Otherwise we're going from dim to bright, so return the saved value */
-    return saved_brightness;
-}
-
 static void update_display_state(struct powerd_display_request *req)
 {
     enum powerd_display_state state = req->state;
-    gboolean use_ab, using_ab;
     int applied_state;
     int ret;
-    int hw_brightness;
-
-    use_ab = ab_enabled(req->flags);
-    using_ab = ab_enabled(internal_state.flags);
-
-    hw_brightness = powerd_get_brightness();
-    if (hw_brightness < 0)
-        hw_brightness = saved_brightness;
-
-    if (!using_ab && hw_brightness != 0 &&
-        (internal_state.flags & POWERD_DISPLAY_FLAG_BRIGHT))
-        saved_brightness = hw_brightness;
-    if (!use_ab)
-        target_brightness = get_target_brightness(
-                    !!(req->flags & POWERD_DISPLAY_FLAG_BRIGHT),
-                    hw_brightness);
 
     applied_state = screen_off_overrides ? DISPLAY_STATE_OFF : state;
 
@@ -214,9 +233,7 @@
         }
 
         powerd_debug("turning off display");
-        if (using_ab)
-            powerd_autobrightness_disable();
-        powerd_set_brightness(0);
+        set_backlight(BL_OFF);
         if (!display_set_power_mode(0, "off")) {
             powerd_warn("failed to set display power mode, not clearing state");
             return;
@@ -232,6 +249,13 @@
         }
         break;
     case POWERD_DISPLAY_STATE_ON:
+        if (ab_enabled(req->flags))
+            target_bl_state = BL_AUTO;
+        else if (req->flags & POWERD_DISPLAY_FLAG_BRIGHT)
+            target_bl_state = BL_BRIGHT;
+        else
+            target_bl_state = BL_DIM;
+
         if (actual_screen_state != POWERD_DISPLAY_STATE_ON) {
             powerd_debug("Requesting active state internally");
             ret = request_sys_state_internal("display-request",
@@ -247,21 +271,10 @@
              * Otherwise we can turn on the screen right away.
              */
             if (!powerd_suspend_active())
-                turn_on_display(use_ab);
+                turn_on_display();
         } else {
-            /* Only changing brightness */
-            if (use_ab) {
-                if (!using_ab)
-                    powerd_autobrightness_enable();
-            } else {
-                if (using_ab) {
-                    powerd_autobrightness_disable();
-                    powerd_set_brightness(target_brightness);
-                } else if ((req->flags & POWERD_DISPLAY_FLAG_BRIGHT) !=
-                           (internal_state.flags & POWERD_DISPLAY_FLAG_BRIGHT)) {
-                    powerd_set_brightness(target_brightness);
-                }
-            }
+            /* Only updating backlight state */
+            set_backlight(target_bl_state);
         }
         break;
     default:
@@ -310,6 +323,12 @@
     internal_state = *req;
 }
 
+static void user_ab_enable(gboolean enable)
+{
+    user_ab_enabled = enable;
+    update_display_state(&internal_state);
+}
+
 static gboolean prox_update_worker(gpointer data)
 {
     unsigned long near = (unsigned long)data;
@@ -376,12 +395,20 @@
     powerd_run_mainloop_sync(apply_override_worker, &ovr_data);
 }
 
+static void set_user_brightness(int brightness)
+{
+    int max = powerd_get_max_brightness();
+    if (brightness > max)
+        brightness = max;
+    user_brightness = brightness;
+    update_display_state(&internal_state);
+}
 
 static gboolean exit_suspend_worker(gpointer unused)
 {
     /* Make sure suspend is still disabled */
     if (!powerd_suspend_active() && powerd_display_enabled())
-        turn_on_display(ab_enabled(internal_state.flags));
+        turn_on_display();
     return FALSE;
 }
 
@@ -392,49 +419,10 @@
 
 int powerd_display_init(void)
 {
-    GValue v = G_VALUE_INIT;
-    int brightness, max_brightness;
     struct stat stats;
 
-    /*
-     * Warning: much hand waving follows
-     *
-     * Right now there's no coherent system brightness policy, so we
-     * just do the best we can. For "dim" brightness we try to read
-     * the value from the Android config files, otherwise we just go
-     * with 5% of maximum. For "bright" brightness, it's more
-     * complicated.
-     *
-     * Our first preference for the bright value is whatever the screen
-     * is currently set to. However, the screen could be off or dimmed
-     * when powerd starts, so we fall back to 75% of maximum when that
-     * happens.
-     */
-
-    if (!device_config_get("screenBrightnessDim", &v)) {
-        if (G_VALUE_HOLDS_UINT(&v))
-            dim_brightness = (int)g_value_get_uint(&v);
-        g_value_unset(&v);
-    }
-
-    max_brightness = powerd_get_max_brightness();
-
-    if (max_brightness <= 0) {
-        powerd_warn("Could not read maximum brightness, guessing at dim/bright values");
-        saved_brightness = 100;
-        if (dim_brightness == 0)
-            dim_brightness = 5;
-    } else {
-        saved_brightness = (3 * max_brightness) / 4;
-        if (dim_brightness == 0)
-            dim_brightness = max_brightness / 20;
-    }
-
-    brightness = powerd_get_brightness();
-    if (brightness > dim_brightness)
-        saved_brightness = brightness;
-
-    target_brightness = saved_brightness;
+    /* Use the current brightness until we're told another value */
+    user_brightness = powerd_get_brightness();
 
     /* decide whether we are running on Mir or SF */
     if (stat(MIR_HINT_PATH, &stats) == 0)
@@ -442,3 +430,24 @@
 
     return 0;
 }
+
+
+/** dbus interfaces **/
+
+gboolean handle_user_autobrightness_enable(PowerdSource *obj,
+                                           GDBusMethodInvocation *invocation,
+                                           gboolean enable)
+{
+    user_ab_enable(enable);
+    g_dbus_method_invocation_return_value(invocation, NULL);
+    return TRUE;
+}
+
+gboolean handle_set_user_brightness(PowerdSource *obj,
+                                    GDBusMethodInvocation *invocation,
+                                    gint brightness)
+{
+    set_user_brightness(brightness);
+    g_dbus_method_invocation_return_value(invocation, NULL);
+    return TRUE;
+}

=== modified file 'src/powerd-internal.h'
--- src/powerd-internal.h	2014-01-03 15:23:38 +0000
+++ src/powerd-internal.h	2014-01-14 03:16:31 +0000
@@ -62,6 +62,7 @@
 void powerd_new_als_event(double lux);
 void powerd_autobrightness_enable(void);
 void powerd_autobrightness_disable(void);
+gboolean powerd_autobrightness_available(void);
 int powerd_autobrightness_init(void);
 void powerd_autobrightness_deinit(void);
 
@@ -71,6 +72,10 @@
 int powerd_get_brightness(void);
 int powerd_get_max_brightness(void);
 int powerd_set_brightness(int brightness);
+int powerd_set_user_brightness(int brightness);
+void powerd_dim_screen(void);
+gboolean handle_get_brightness_params(PowerdSource *obj,
+                                      GDBusMethodInvocation *invocation);
 
 /* Display functions */
 void powerd_brightness_set_value(gint value);
@@ -81,6 +86,12 @@
 void powerd_proximity_event(gboolean near);
 void powerd_display_set_override(enum powerd_override_reason reason);
 void powerd_display_clear_override(enum powerd_override_reason reason);
+gboolean handle_user_autobrightness_enable(PowerdSource *obj,
+                                           GDBusMethodInvocation *invocation,
+                                           gboolean enable);
+gboolean handle_set_user_brightness(PowerdSource *obj,
+                                    GDBusMethodInvocation *invocation,
+                                    gint brightness);
 
 /* Display request functions */
 int powerd_add_display_request(struct powerd_display_request *request,

=== modified file 'src/powerd-object.c'
--- src/powerd-object.c	2013-08-12 02:46:09 +0000
+++ src/powerd-object.c	2014-01-14 03:16:31 +0000
@@ -124,14 +124,14 @@
 
     owner = g_dbus_method_invocation_get_sender(invocation);
     ret = powerd_client_ack(owner, state);
-    if (ret) {
-        const char *msg = (ret == -EINVAL) ? "Invalid state" :
-                                             "Client not registered";
+    if (ret)
         g_dbus_method_invocation_return_error(invocation, G_DBUS_ERROR,
-                                              G_DBUS_ERROR_INVALID_ARGS, msg);
-    } else {
+                                              G_DBUS_ERROR_INVALID_ARGS,
+                                              ret == -EINVAL ?
+                                              "Invalid state" :
+                                              "Client not registered");
+    else
         g_dbus_method_invocation_return_value(invocation, NULL);
-    }
     return TRUE;
 }
 
@@ -181,6 +181,12 @@
         G_CALLBACK(handle_get_sys_request_stats), powerd_source);
     g_signal_connect(G_OBJECT(powerd_source->priv->skel), "handle-get-disp-request-stats",
         G_CALLBACK(handle_get_disp_request_stats), powerd_source);
+    g_signal_connect(G_OBJECT(powerd_source->priv->skel), "handle-user-autobrightness-enable",
+        G_CALLBACK(handle_user_autobrightness_enable), powerd_source);
+    g_signal_connect(G_OBJECT(powerd_source->priv->skel), "handle-get-brightness-params",
+        G_CALLBACK(handle_get_brightness_params), powerd_source);
+    g_signal_connect(G_OBJECT(powerd_source->priv->skel), "handle-set-user-brightness",
+        G_CALLBACK(handle_set_user_brightness), powerd_source);
 
     powerd_dbus_init_complete();
 }