From f1a9ebd2678c04de88de11533693b6d818244b38 Mon Sep 17 00:00:00 2001
From: Sepherosa Ziehau <sephe@dragonflybsd.org>
Date: Sun, 16 Aug 2015 21:22:35 +0800
Subject: [PATCH] powerd: Set backlight to the specified value, if AC line is
 unplugged.

---
 usr.sbin/powerd/powerd.8 |  6 ++++-
 usr.sbin/powerd/powerd.c | 57 ++++++++++++++++++++++++++++++++++++++--
 2 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/usr.sbin/powerd/powerd.8 b/usr.sbin/powerd/powerd.8
index 6bb340dd7a..ad7d315ce1 100644
--- a/usr.sbin/powerd/powerd.8
+++ b/usr.sbin/powerd/powerd.8
@@ -1,7 +1,7 @@
 .\" (c) Copyright 2010 by Matthew Dillon and Dima Ruban.  Permission to
 .\"    use and distribute based on the DragonFly copyright.
 .\"
-.Dd July 17, 2015
+.Dd August 16, 2015
 .Dt POWERD 8
 .Os
 .Sh NAME
@@ -10,6 +10,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl cdeftQ
+.Op Fl b Ar backlight_percentage
 .Op Fl h Ar highest_freq
 .Op Fl l Ar lowest_freq
 .Op Fl p Ar hysteresis
@@ -37,6 +38,9 @@ and shutdown the machine after lingering for a little while
 .Pp
 The options are as follows:
 .Bl -tag -width ".Fl p Ar hysteresis"
+.It Fl b Ar backlight_percentage
+Set backlight to the specified percentage,
+if AC line is not plugged in.
 .It Fl c
 Enable mwait C-state hint adjustment,
 if it is available.
diff --git a/usr.sbin/powerd/powerd.c b/usr.sbin/powerd/powerd.c
index 436bd7653d..91d5580121 100644
--- a/usr.sbin/powerd/powerd.c
+++ b/usr.sbin/powerd/powerd.c
@@ -159,6 +159,9 @@ static int BatShutdownLinger = -1;
 static int BatShutdownLingerSet = 60; /* unit: sec */
 static int BatShutdownLingerCnt;
 static int BatShutdownAudioAlert = 1;
+static int BackLightPct = 100;
+static int OldBackLightLevel;
+static int BackLightDown;
 
 static void sigintr(int signo);
 
@@ -174,8 +177,11 @@ main(int ac, char **av)
 	srt = 8.0;	/* time for samples - 8 seconds */
 	pollrate = 1.0;	/* polling rate in seconds */
 
-	while ((ch = getopt(ac, av, "cdefh:l:p:r:tu:B:L:P:QT:")) != -1) {
+	while ((ch = getopt(ac, av, "b:cdefh:l:p:r:tu:B:L:P:QT:")) != -1) {
 		switch(ch) {
+		case 'b':
+			BackLightPct = strtol(optarg, NULL, 10);
+			break;
 		case 'c':
 			AdjustCstate = 1;
 			break;
@@ -246,6 +252,11 @@ main(int ac, char **av)
 		exit(1);
 	}
 
+	if (BackLightPct > 100 || BackLightPct <= 0) {
+		fprintf(stderr, "Invalid backlight setting, ignore\n");
+		BackLightPct = 100;
+	}
+
 	TriggerDown = TriggerUp - (TriggerUp * (double) Hysteresis / 100);
 
 	/*
@@ -589,7 +600,8 @@ usage(void)
 	    "[-h highest_freq] [-l lowest_freq] "
 	    "[-r poll_interval] [-u trigger_up] "
 	    "[-B min_battery_life] [-L low_battery_linger] "
-	    "[-P battery_poll_interval] [-T sample_interval]\n");
+	    "[-P battery_poll_interval] [-T sample_interval] "
+	    "[-b backlight]\n");
 	exit(1);
 }
 
@@ -704,9 +716,50 @@ mon_battery(void)
 	if (acline) {
 		BatShutdownLinger = -1;
 		BatShutdownLingerCnt = 0;
+		if (BackLightDown) {
+			BackLightDown = 0;
+			sysctlbyname("hw.backlight_level", NULL, NULL,
+			    &OldBackLightLevel, sizeof(OldBackLightLevel));
+		}
 		return 1;
 	}
 
+	if (!BackLightDown && BackLightPct != 100) {
+		int backlight_max, backlight;
+
+		len = sizeof(backlight_max);
+		if (sysctlbyname("hw.backlight_max", &backlight_max, &len,
+		    NULL, 0) < 0) {
+			/* No more backlight adjustment */
+			BackLightPct = 100;
+			goto after_backlight;
+		}
+
+		len = sizeof(OldBackLightLevel);
+		if (sysctlbyname("hw.backlight_level", &OldBackLightLevel, &len,
+		    NULL, 0) < 0) {
+			/* No more backlight adjustment */
+			BackLightPct = 100;
+			goto after_backlight;
+		}
+
+		backlight = (backlight_max * BackLightPct) / 100;
+		if (backlight >= OldBackLightLevel) {
+			/* No more backlight adjustment */
+			BackLightPct = 100;
+			goto after_backlight;
+		}
+
+		if (sysctlbyname("hw.backlight_level", NULL, NULL,
+		    &backlight, sizeof(backlight)) < 0) {
+			/* No more backlight adjustment */
+			BackLightPct = 100;
+			goto after_backlight;
+		}
+		BackLightDown = 1;
+	}
+after_backlight:
+
 	len = sizeof(life);
 	if (sysctlbyname("hw.acpi.battery.life", &life, &len, NULL, 0) < 0)
 		return 1;
-- 
2.41.0