ENGR00222134 MX6x - Fix race-conditions in low power code.

Fix couple of race-conditions associated with low power IDLE code:
1. Ensure that bus freq mutex is used in the suspend/resume function
2. Ensure that the usecount of pll2 is incremented/decremented when
ARM is switched to run from PLL2_PFD_400. And PLL2 is enabled/disabled
when necessary.

Signed-off-by: Ranjani Vaidyanathan <ra5478@freescale.com>

3 files changed, 46 insertions, 8 deletions

diff --git a/arch/arm/mach-mx6/bus_freq.c b/arch/arm/mach-mx6/bus_freq.c
index 23f56d5deaf1..151b4ee27eb6 100644
--- a/arch/arm/mach-mx6/bus_freq.c
+++ b/arch/arm/mach-mx6/bus_freq.c
@@ -501,6 +501,8 @@ static int busfreq_suspend(struct platform_device *pdev, pm_message_t message)
 static int bus_freq_pm_notify(struct notifier_block *nb, unsigned long event,
 	void *dummy)
 {
+	mutex_lock(&bus_freq_mutex);
+
 	if (event == PM_SUSPEND_PREPARE) {
 		set_high_bus_freq(1);
 		busfreq_suspended = 1;
@@ -508,6 +510,8 @@ static int bus_freq_pm_notify(struct notifier_block *nb, unsigned long event,
 		busfreq_suspended = 0;
 	}
 
+	mutex_unlock(&bus_freq_mutex);
+
 	return NOTIFY_OK;
 }
 static int busfreq_resume(struct platform_device *pdev)
diff --git a/arch/arm/mach-mx6/clock.c b/arch/arm/mach-mx6/clock.c
index c2bf20177909..8b75aee78964 100644
--- a/arch/arm/mach-mx6/clock.c
+++ b/arch/arm/mach-mx6/clock.c
@@ -1261,7 +1261,16 @@ static int _clk_arm_set_rate(struct clk *clk, unsigned long rate)
 		  * PLL2_PFD_400M.
 		  */
 		if (pll1_sw_clk.parent != &pll2_pfd_400M) {
-			pll2_pfd_400M.enable(&pll2_pfd_400M);
+			if (pll2_pfd_400M.usecount == 0) {
+				/* Check if PLL2 needs to be enabled also. */
+				if (pll2_528_bus_main_clk.usecount == 0)
+					pll2_528_bus_main_clk.enable(&pll2_528_bus_main_clk);
+				/* Ensure parent usecount is
+				  * also incremented.
+				  */
+				pll2_528_bus_main_clk.usecount++;
+				pll2_pfd_400M.enable(&pll2_pfd_400M);
+			}
 			pll2_pfd_400M.usecount++;
 			arm_needs_pll2_400 = true;
 			pll1_sw_clk.set_parent(&pll1_sw_clk, &pll2_pfd_400M);
@@ -1288,11 +1297,19 @@ static int _clk_arm_set_rate(struct clk *clk, unsigned long rate)
 		/* Make sure pll1_sw_clk is from pll1_sys_main_clk */
 		pll1_sw_clk.set_parent(&pll1_sw_clk, &pll1_sys_main_clk);
 		pll1_sw_clk.parent = &pll1_sys_main_clk;
-		if (arm_needs_pll2_400)
+		if (arm_needs_pll2_400) {
 			pll2_pfd_400M.usecount--;
+			if (pll2_pfd_400M.usecount == 0) {
+				pll2_pfd_400M.disable(&pll2_pfd_400M);
+				/* Ensure parent usecount is
+				  * also decremented.
+				  */
+				pll2_528_bus_main_clk.usecount--;
+				if (pll2_528_bus_main_clk.usecount == 0)
+					pll2_528_bus_main_clk.disable(&pll2_528_bus_main_clk);
+			}
+		}
 		arm_needs_pll2_400 = false;
-		if (pll2_pfd_400M.usecount == 0)
-			pll2_pfd_400M.disable(&pll2_pfd_400M);
 	}
 	parent_rate = clk_get_rate(clk->parent);
 	div = parent_rate / rate;
diff --git a/arch/arm/mach-mx6/clock_mx6sl.c b/arch/arm/mach-mx6/clock_mx6sl.c
index 43b2bd1baac2..6bd818ae7139 100755
--- a/arch/arm/mach-mx6/clock_mx6sl.c
+++ b/arch/arm/mach-mx6/clock_mx6sl.c
@@ -1167,7 +1167,16 @@ static int _clk_arm_set_rate(struct clk *clk, unsigned long rate)
 		  * PLL2_PFD2_400M.
 		  */
 		if (pll1_sw_clk.parent != &pll2_pfd2_400M) {
-			pll2_pfd2_400M.enable(&pll2_pfd2_400M);
+			if (pll2_pfd2_400M.usecount == 0) {
+				/* Check if PLL2 needs to be enabled also. */
+				if (pll2_528_bus_main_clk.usecount == 0)
+					pll2_528_bus_main_clk.enable(&pll2_528_bus_main_clk);
+				/* Ensure parent usecount is
+				  * also incremented.
+				  */
+				pll2_528_bus_main_clk.usecount++;
+				pll2_pfd2_400M.enable(&pll2_pfd2_400M);
+			}
 			arm_needs_pll2_400 = true;
 			pll2_pfd2_400M.usecount++;
 			pll1_sw_clk.set_parent(&pll1_sw_clk, &pll2_pfd2_400M);
@@ -1192,11 +1201,19 @@ static int _clk_arm_set_rate(struct clk *clk, unsigned long rate)
 		pll1_sw_clk.set_parent(&pll1_sw_clk, &pll1_sys_main_clk);
 		pll1_sw_clk.parent = &pll1_sys_main_clk;
 
-		if (arm_needs_pll2_400)
+		if (arm_needs_pll2_400) {
 			pll2_pfd2_400M.usecount--;
+			if (pll2_pfd2_400M.usecount == 0) {
+				pll2_pfd2_400M.disable(&pll2_pfd2_400M);
+				/* Ensure parent usecount is
+				  * also decremented.
+				  */
+				pll2_528_bus_main_clk.usecount--;
+				if (pll2_528_bus_main_clk.usecount == 0)
+					pll2_528_bus_main_clk.disable(&pll2_528_bus_main_clk);
+			}
+		}
 		arm_needs_pll2_400 = false;
-		if (pll2_pfd2_400M.usecount == 0)
-			pll2_pfd2_400M.disable(&pll2_pfd2_400M);
 	}
 	parent_rate = clk_get_rate(clk->parent);
 	div = parent_rate / rate;