Use the timeout API as a oneshot for headphone plug debouncing. Set at 1s for now which seems comfortable and was good for meg-fx but target-specific adjustment is easy enough (my 3G hp jack is dead so I can't check that one :( ). Do some minor rearrangements for init safety and consistency.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@16178 a1c6a512-1295-4272-9138-f99709370657

firmware/drivers/button.c

@@ -61,7 +61,7 @@ static bool remote_filter_first_keypress;
 #endif
 #endif /* HAVE_BACKLIGHT */
 #ifdef HAVE_HEADPHONE_DETECTION
-bool phones_present = false;
+static bool phones_present = false;
 #endif
 
 /* how long until repeat kicks in, in ticks */
@@ -79,6 +79,20 @@ static int button_read(int *data);
 static int button_read(void);
 #endif
 
+#if defined(HAVE_HEADPHONE_DETECTION)
+static struct timeout hp_detect_timeout; /* Debouncer for headphone plug/unplug */
+/* This callback can be used for many different functions if needed -
+   just check to which object tmo points */
+static bool btn_detect_callback(struct timeout *tmo)
+{
+    /* Try to post only transistions */
+    const long id = tmo->data ? SYS_PHONE_PLUGGED : SYS_PHONE_UNPLUGGED;
+    queue_remove_from_head(&button_queue, id);
+    queue_post(&button_queue, id, 0);
+    return false;
+}
+#endif
+
 static void button_tick(void)
 {
     static int count = 0;
@@ -109,29 +123,22 @@ static void button_tick(void)
     }
 #endif
 
-#ifdef HAVE_HEADPHONE_DETECTION
-    if ( headphones_inserted() )
-    {
-        if (! phones_present )
-        {
-            queue_post(&button_queue, SYS_PHONE_PLUGGED, 0);
-            phones_present = true;
-        }
-    } else {
-        if ( phones_present )
-        {
-            queue_post(&button_queue, SYS_PHONE_UNPLUGGED, 0);
-            phones_present = false;
-        }
-    }
-#endif
-
 #ifdef HAVE_BUTTON_DATA
     btn = button_read(&data);
 #else
     btn = button_read();
 #endif
 
+#if defined(HAVE_HEADPHONE_DETECTION)
+    if (headphones_inserted() != phones_present)
+    {
+        /* Use the autoresetting oneshot to debounce the detection signal */
+        phones_present = !phones_present;
+        timeout_register(&hp_detect_timeout, btn_detect_callback,
+                         HZ, phones_present);
+    }
+#endif
+
     /* Find out if a key has been released */
     diff = btn ^ lastbtn;
     if(diff && (btn & diff) == 0)
@@ -369,14 +376,15 @@ intptr_t button_get_data(void)
 
 void button_init(void)
 {
+    /* Init used objects first */
+    queue_init(&button_queue, true);
+
 #ifdef HAVE_BUTTON_DATA
     int temp;
 #endif
     /* hardware inits */
     button_init_device();
 
-    queue_init(&button_queue, true);
-
 #ifdef HAVE_BUTTON_DATA
     button_read(&temp);
     lastbtn = button_read(&temp);
@@ -385,7 +393,6 @@ void button_init(void)
     lastbtn = button_read();
 #endif
     
-    tick_add_task(button_tick);
     reset_poweroff_timer();
 
 #ifdef HAVE_LCD_BITMAP
@@ -397,6 +404,9 @@ void button_init(void)
     remote_filter_first_keypress = false;
 #endif    
 #endif
+
+    /* Start polling last */
+    tick_add_task(button_tick);
 }
 
 #ifdef HAVE_LCD_BITMAP /* only bitmap displays can be flipped */

firmware/export/config.h

@@ -489,4 +489,11 @@
 
 #endif /* NUM_CORES */
 
+#ifdef HAVE_HEADPHONE_DETECTION
+/* Timeout objects required if headphone detection is enabled */
+#ifndef INCLUDE_TIMEOUT_API
+#define INCLUDE_TIMEOUT_API
+#endif
+#endif /* HAVE_HEADPHONE_DETECTION */
+
 #endif /* __CONFIG_H__ */

firmware/target/arm/s3c2440/gigabeat-fx/button-meg-fx.c

@@ -76,6 +76,16 @@ int button_read_device(void)
     /* Only one button can be sensed at a time on the remote. */
     /* Need to filter the remote button because the ADC is so fast */
     remote_adc = adc_read(ADC_HPREMOTE);
+
+    if (remote_adc != ADC_READ_ERROR)
+    {
+        /* If there is nothing in the headphone socket, the ADC reads high */
+        if (remote_adc < 940)
+            headphones_detect = true;
+        else
+            headphones_detect = false;
+    }
+
     btn = remote_buttons[(remote_adc + 64) / 128];
     if (btn != lastbutton)
     {
@@ -136,14 +146,5 @@ int button_read_device(void)
 
 bool headphones_inserted(void)
 {
-    unsigned short remote_adc = adc_read(ADC_HPREMOTE);
-    if (remote_adc != ADC_READ_ERROR)
-    {
-        /* If there is nothing in the headphone socket, the ADC reads high */
-        if (remote_adc < 940)
-            headphones_detect = true;
-        else
-            headphones_detect = false;
-    }
     return headphones_detect;
 }