modules: display: also use dpms when (un)blanking

When using DRM for display management, as opposed to just fbdev, just
blanking /dev/fb0 is not enough to make devices actually enter deeper
idle states, DPMS does the trick by telling X11 to send the right DRM
ioctls.

Makefile

@@ -79,7 +79,7 @@ MODULE_CFLAGS := $(COMMON_CFLAGS)
 MODULE_CFLAGS += -fPIC -shared
 MODULE_CFLAGS += -I.
 MODULE_CFLAGS += $$(pkg-config glib-2.0 gmodule-2.0 dbus-1 dbus-glib-1 gconf-2.0 upower-glib --cflags)
-MODULE_LDFLAGS := $$(pkg-config glib-2.0 gmodule-2.0 dbus-1 dbus-glib-1 gconf-2.0 upower-glib libcal --libs)
+MODULE_LDFLAGS := $$(pkg-config glib-2.0 gmodule-2.0 dbus-1 dbus-glib-1 gconf-2.0 upower-glib libcal x11 xext --libs)
 MODULE_LIBS := datapipe.c mce-hal.c mce-log.c mce-dbus.c mce-conf.c mce-gconf.c median_filter.c mce-lib.c
 MODULE_HEADERS := datapipe.h mce-hal.h mce-log.h mce-dbus.h mce-conf.h mce-gconf.h mce.h median_filter.h mce-lib.h
 

modules/display.c

@@ -28,6 +28,8 @@
 #include <string.h>
 #include <unistd.h>
 #include <linux/fb.h>
+#include <X11/Xlib.h>
+#include <X11/extensions/dpms.h>
 #include <sys/ioctl.h>
 #include <mce/mode-names.h>
 #include "mce.h"
@@ -365,6 +367,38 @@ static gboolean backlight_ioctl(int value)
 	return status;
 }
 
+/* Set DPMS mode for X11 display to on or off
+ *
+ * @params dpms_on To force the mode into on or off (blanked) mode.
+ */
+static void dpms_set_display_on(gboolean dpms_on)
+{
+	Display* dpy = NULL;
+
+	dpy = XOpenDisplay(NULL);
+	if (dpy == NULL) {
+		dpy = XOpenDisplay(":0.0");
+	}
+
+	if (dpy == NULL) {
+		mce_log(LL_INFO, "%s: unable to open display", __func__);
+		return;
+	}
+
+	if (DPMSCapable(dpy)) {
+		DPMSEnable(dpy);
+		if (dpms_on) {
+			DPMSForceLevel(dpy, DPMSModeOn);
+		} else {
+			usleep(100000); // from xset
+			DPMSForceLevel(dpy, DPMSModeOff);
+		}
+	}
+
+	XCloseDisplay(dpy);
+}
+
+
 /**
  * Timeout callback for the brightness fade
  *
@@ -380,6 +414,7 @@ static gboolean brightness_fade_timeout_cb(gpointer data)
 
 	if ((cached_brightness <= 0) && (target_brightness != 0)) {
 		backlight_ioctl(FB_BLANK_UNBLANK);
+		dpms_set_display_on(TRUE);
 	}
 
 	if ((cached_brightness == -1) ||
@@ -398,6 +433,7 @@ static gboolean brightness_fade_timeout_cb(gpointer data)
 
 	if (cached_brightness == 0) {
 		backlight_ioctl(FB_BLANK_POWERDOWN);
+		dpms_set_display_on(FALSE);
 	}
 
 	if (retval == FALSE)
@@ -479,6 +515,7 @@ static void display_blank(void)
 	target_brightness = 0;
 	mce_write_number_string_to_file(brightness_file, 0);
 	backlight_ioctl(FB_BLANK_POWERDOWN);
+	dpms_set_display_on(FALSE);
 }
 
 /**
@@ -488,6 +525,7 @@ static void display_dim(void)
 {
 	if (cached_brightness == 0) {
 		backlight_ioctl(FB_BLANK_UNBLANK);
+		dpms_set_display_on(TRUE);
 	}
 
 	update_brightness_fade((maximum_display_brightness *
@@ -506,6 +544,7 @@ static void display_unblank(void)
 		backlight_ioctl(FB_BLANK_UNBLANK);
 		mce_write_number_string_to_file(brightness_file,
 						set_brightness);
+		dpms_set_display_on(TRUE);
 	} else {
 		update_brightness_fade(set_brightness);
 	}