Solve issue with CPU using 100% resources when autodimm was activated. This resolves issue TDE/tde#136.

The problem was hardware dependent and only noticable when the backlight
card has hundreds or thousands of steps. This was causing non-stop
calls to setBrightness, which did not have enough CPU time to complete
its task before the next call, resulting in the CPU eating up all
resources, non stop.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

src/tdepowersave.cpp

@@ -150,7 +150,8 @@ tdepowersave::tdepowersave( bool force_acpi_check, bool trace_func ) : KSystemTr
 	BAT_WARN_ICON_Timer = new TQTimer(this);
 	connect(BAT_WARN_ICON_Timer, TQT_SIGNAL(timeout()), this, TQT_SLOT(do_setIconBG()));
 
-	AUTODIMM_Timer = new TQTimer(this);
+	m_autoDimmTimer = new TQTimer(this);
+	connect(m_autoDimmTimer, TQT_SIGNAL(timeout()), this, TQT_SLOT(do_dimm()));
 
 	initMenu();
 	update();
@@ -169,6 +170,7 @@ tdepowersave::~tdepowersave(){
 	delete display;
 	delete settings;
 	delete autoSuspend;
+	delete m_autoDimmTimer;
 #ifdef ENABLE_YAST_ENTRY
 	delete yast2;
 #endif
@@ -1074,25 +1076,22 @@ void tdepowersave::do_downDimm() {
 	kdDebugFuncIn(trace);
 
 	if (hwinfo->supportBrightness()) {
-		if (!AUTODIMM_Timer->isActive()) {
+		if (!m_autoDimmTimer->isActive()) {
 			int dimmToLevel = (int)round(hwinfo->getMaxBrightnessLevel() * settings->autoDimmTo / 100.0);
 
 			// check if we really need to dimm down
 			if (dimmToLevel < hwinfo->getCurrentBrightnessLevel()) {
-				int steps = hwinfo->getCurrentBrightnessLevel() - dimmToLevel;
+				m_dimmRequestedLevel = dimmToLevel;
-				int timePerStep = (1500 / steps);
+				m_dimmStep = (hwinfo->getCurrentBrightnessLevel() - dimmToLevel) / 10 + 1;
-
+				m_dimmTimeoutCounter = 0;
 				autoDimmDown = true;
-
+				m_autoDimmTimer->start(100, false);
-				AUTODIMM_Timer = new TQTimer(this);
-				connect(AUTODIMM_Timer, TQT_SIGNAL(timeout()), this, TQT_SLOT(do_dimm()));
-				AUTODIMM_Timer->start(timePerStep, false);
 			} else {
 				kdWarning() << "Don't dimm down, current level is already lower than requested Level" << endl;
 			}
 		} else {
 			// wait until the timer is stopped, try later!
-			TQTimer::singleShot(1500, this, TQT_SLOT(do_downDimm()));
+			TQTimer::singleShot(2000, this, TQT_SLOT(do_downDimm()));
 		}
 	}
 
@@ -1113,28 +1112,24 @@ void tdepowersave::do_upDimm() {
 	//NOTE we go back to the value of the scheme and not the last on, to reduce trouble with the scheme
 
 	if (hwinfo->supportBrightness()) {
-		if (!AUTODIMM_Timer->isActive()) {
+		if (!m_autoDimmTimer->isActive()) {
-			int dimmToLevel = (int)round(hwinfo->getMaxBrightnessLevel() * settings->autoDimmTo / 100.0);
+			int dimmToLevel = (int)round(hwinfo->getMaxBrightnessLevel() * settings->brightnessValue / 100.0);
 
 			// check if we really need to dimm up
 			if (dimmToLevel > hwinfo->getCurrentBrightnessLevel()) {
-				int steps = dimmToLevel - hwinfo->getCurrentBrightnessLevel();
+				m_dimmRequestedLevel = dimmToLevel;
-				int timePerStep = (750 / steps);
+				m_dimmStep = (dimmToLevel - hwinfo->getCurrentBrightnessLevel()) / 10 + 1;
-
+				m_dimmTimeoutCounter = 0;
 				autoDimmDown = false;
-
+				m_autoDimmTimer->start(100, false);
-				AUTODIMM_Timer = new TQTimer(this);
-				connect(AUTODIMM_Timer, TQT_SIGNAL(timeout()), this, TQT_SLOT(do_dimm()));
-				AUTODIMM_Timer->start(timePerStep, false);
-
-				// start autodimm again
-				setAutoDimm(false);
 			} else {
 				kdWarning() << "Don't dimm up, current level is already above requested Level" << endl;
 			}
+			// start autodimm again
+			setAutoDimm(false);
 		} else {
 			// wait until the timer is stopped, try later!
-			TQTimer::singleShot(750, this, TQT_SLOT(do_downDimm()));
+			TQTimer::singleShot(2000, this, TQT_SLOT(do_downDimm()));
 		}
 	}
 
@@ -1151,14 +1146,22 @@ void tdepowersave::do_upDimm() {
 void tdepowersave::do_dimm() {
 	kdDebugFuncIn(trace);
 
+	if (m_dimmStep <= 0 || m_dimmTimeoutCounter > 30)
+	{
+		m_autoDimmTimer->stop();
+		return;
+	}
+
+	++m_dimmTimeoutCounter;
 	int current = hwinfo->getCurrentBrightnessLevel();
 
 	if (autoDimmDown) {
 		// dimm the display down
-		if (current > (int)round(hwinfo->getMaxBrightnessLevel() * settings->autoDimmTo / 100.0)) {
+		if (current > 0 && current > (m_dimmRequestedLevel * 1.005)) {
-			hwinfo->setBrightnessLevel(current -1);
+			hwinfo->setBrightnessLevel(current - m_dimmStep);
 		} else {
-			AUTODIMM_Timer->stop();
+			m_autoDimmTimer->stop();
+			m_dimmStep = 0;
 
 			// start checking if the user get active again
 			// NOTE: we start this here because the X-Server detect brightness changes as
@@ -1167,10 +1170,11 @@ void tdepowersave::do_dimm() {
 		}
 	} else {
 		// dimm the display up
-		if (current < (int)round(hwinfo->getMaxBrightnessLevel() * settings->autoDimmTo / 100.0)) {
+		if (current < (m_dimmRequestedLevel * 0.995)) {
-			hwinfo->setBrightnessLevel(current +1);
+			hwinfo->setBrightnessLevel(current + m_dimmStep);
 		} else {
-			AUTODIMM_Timer->stop();
+			m_autoDimmTimer->stop();
+			m_dimmStep = 0;
 		}
 	}
 

src/tdepowersave.h

@@ -159,6 +159,11 @@ private:
 	*/
 	bool autoDimmDown;
 
+	// used during dimm down/up transitions
+	int m_dimmRequestedLevel;
+	int m_dimmStep;
+	int m_dimmTimeoutCounter;
+
 	//! to temporary hold the resume result
 	int resume_result;
 
@@ -266,12 +271,12 @@ private:
 	* The timerinterval is defined in \ref BAT_icon_BG_intervall .
 	*/
 	TQTimer *BAT_WARN_ICON_Timer;
+
 	//! Timer to dimm down/up the brightness
 	/*!
-	 * This timer is used dimm the display up and down. The timerinterval
+	 * This timer is used to dimm the display up and down.
-         * depends on calculated timePerStep in the calling function.
 	 */
-	TQTimer *AUTODIMM_Timer;
+	TQTimer *m_autoDimmTimer;
 
 	//! draw all icon related things for \ref redrawPixmap()
 	void drawIcon();