devfreq: Weight stall cycles more for GPU bus DCVS

Update GPU Bus DCVS to weight high stall cycles (as a percentage
of total bus usage) heavier in order to vote up the bus when the
GPU is stalling a lot waiting for data.

Change-Id: I8a331a48a1ab737c51f1001ea1991f09af9ef900
Signed-off-by: Kyle Piefer <kpiefer@codeaurora.org>

drivers/devfreq/governor_gpubw_mon.c

@@ -24,6 +24,7 @@
 #define HIST                    5
 #define TARGET                  80
 #define CAP                     75
+#define WAIT_THRESHOLD          10
 /* AB vote is in multiple of BW_STEP Mega bytes */
 #define BW_STEP                 160
 
@@ -67,6 +68,7 @@ static int devfreq_gpubw_get_target(struct devfreq *df,
 	int act_level;
 	int norm_max_cycles;
 	int norm_cycles;
+	int wait_active_percent;
 	int gpu_percent;
 	/*
 	 * Normalized AB should at max usage be the gpu_bimc frequency in MHz.
@@ -99,6 +101,8 @@ static int devfreq_gpubw_get_target(struct devfreq *df,
 			(unsigned int) priv->bus.total_time;
 	norm_cycles = (unsigned int)(priv->bus.ram_time + priv->bus.ram_wait) /
 			(unsigned int) priv->bus.total_time;
+	wait_active_percent = (100 * (unsigned int)priv->bus.ram_wait) /
+			(unsigned int) priv->bus.ram_time;
 	gpu_percent = (100 * (unsigned int)priv->bus.gpu_time) /
 			(unsigned int) priv->bus.total_time;
 
@@ -117,7 +121,8 @@ static int devfreq_gpubw_get_target(struct devfreq *df,
 		act_level = (act_level < 0) ? 0 : act_level;
 		act_level = (act_level >= priv->bus.num) ?
 		(priv->bus.num - 1) : act_level;
-		if (norm_cycles > priv->bus.up[act_level] &&
+		if ((norm_cycles > priv->bus.up[act_level] ||
+				wait_active_percent > WAIT_THRESHOLD) &&
 				gpu_percent > CAP)
 			bus_profile->flag = DEVFREQ_FLAG_FAST_HINT;
 		else if (norm_cycles < priv->bus.down[act_level] && level)