imx233: Implement mutex for cpu_boost_lock/unlock

Playing AAC-HE files resulted in a race condition between
audio/codec/buffering for set_cpu_frequency

Change-Id: I35e1c1fd18db623e2990c305acdca03f57184d0d

2 files changed, 34 insertions, 0 deletions

diff --git a/firmware/target/arm/imx233/system-imx233.c b/firmware/target/arm/imx233/system-imx233.c
index 4e1583d568..3ac5d0e557 100644
--- a/firmware/target/arm/imx233/system-imx233.c
+++ b/firmware/target/arm/imx233/system-imx233.c
@@ -53,6 +53,8 @@
 #define WATCHDOG_HW_DELAY   (10 * HZ)
 #define WATCHDOG_SW_DELAY   (5 * HZ)
 
+static struct mutex cpufreq_mtx;
+
 void UIE(unsigned int pc, unsigned int num);
 
 static void woof_woof(void)
@@ -183,6 +185,7 @@ void system_init(void)
      * The main() will naturally set cpu speed to normal after kernel_init()
      * so don't bother if the cpu is running at 24MHz here.
      * Make sure IO clock is running at expected speed */
+    mutex_init(&cpufreq_mtx);
     imx233_clkctrl_init();
     imx233_clkctrl_enable(CLK_PLL, true);
 #if IMX233_SUBTARGET >= 3700
@@ -364,6 +367,20 @@ void imx233_set_cpu_frequency(long frequency)
 }
 
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
+bool set_cpu_frequency__lock(void)
+{
+    if (get_processor_mode() != CPU_MODE_THREAD_CONTEXT)
+        return false;
+
+    mutex_lock(&cpufreq_mtx);
+    return true;
+}
+
+void set_cpu_frequency__unlock(void)
+{
+    mutex_unlock(&cpufreq_mtx);
+}
+
 void set_cpu_frequency(long frequency)
 {
     return imx233_set_cpu_frequency(frequency);
diff --git a/firmware/target/arm/imx233/system-target.h b/firmware/target/arm/imx233/system-target.h
index ee2df9a3e9..45dc58698a 100644
--- a/firmware/target/arm/imx233/system-target.h
+++ b/firmware/target/arm/imx233/system-target.h
@@ -54,6 +54,23 @@ bool imx233_us_elapsed(uint32_t ref, unsigned us_delay);
 void imx233_reset_block(volatile uint32_t *block_reg);
 void imx233_enable_usb_controller(bool enable);
 void imx233_enable_usb_phy(bool enable);
+
+#ifdef HAVE_ADJUSTABLE_CPU_FREQ
+#define CPU_BOOST_LOCK_DEFINED
+
+static inline bool cpu_boost_lock(void)
+{
+    bool set_cpu_frequency__lock(void);
+    return set_cpu_frequency__lock();
+}
+
+static inline void cpu_boost_unlock(void)
+{
+    void set_cpu_frequency__unlock(void);
+    set_cpu_frequency__unlock();
+}
+#endif /* HAVE_ADJUSTABLE_CPU_FREQ */
+
 // NOTE: this is available even if HAVE_ADJUSTABLE_CPU_FREQ is undef
 void imx233_set_cpu_frequency(long frequency);