[display] Reject LPM mode when lockscreen is not on screen. Fixes JB#…

…21043

When LPM is in use and gets triggered immediately after ending a call,
display gets dimmed and coloring changes but call ui is still shown on
screen (and can't be interacted with).

Reject attempts to invoke LPM state if it is expected that call or
alarm ui - which are layered above locksreen - are on screen.

When LPM state is activated, allow UI side some time to hide any
active applications. But if that does not happen, exit from LPM by
blanking screen.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

modules/display.c

@@ -154,6 +154,19 @@
  */
 #define COMPOSITOR_STM_DBUS_RETRY_DELAY 5000
 
+/** How long hiding applications is allowed to take on entry to LPM
+ *
+ * The LPM UI is effectively the same as lockscreen. If some application
+ * remains on top after LPM activation, we have ghost UI instead of LPM.
+ *
+ * The known problem spot is: Call UI after ending a call.
+ *
+ * The delay should be long enough not to cause false positives, and
+ * short enough not to leave users too much time to try to interact
+ * with an application that is not going to get any touch events.
+ */
+#define LPM_SANITIZE_DELAY 600 // [ms]
+
 /* ========================================================================= *
  * TYPEDEFS
  * ========================================================================= */
@@ -432,6 +445,15 @@ static void                mdy_datapipe_quit(void);
 
 static void                mdy_fbdev_rethink(void);
 
+/* ------------------------------------------------------------------------- *
+ * LOW_POWER_MODE
+ * ------------------------------------------------------------------------- */
+
+static bool                mdy_lpm_allowed(void);
+static gboolean            mdy_lpm_sanitize_cb(gpointer aptr);
+static void                mdy_lpm_schedule_sanitize(void);
+static void                mdy_lpm_cancel_sanitize(void);
+
 /* ------------------------------------------------------------------------- *
  * HIGH_BRIGHTNESS_MODE
  * ------------------------------------------------------------------------- */
@@ -1356,6 +1378,9 @@ xlat(int src_lo, int src_hi, int dst_lo, int dst_hi, int val)
  * DATAPIPE_TRACKING
  * ========================================================================= */
 
+/** Cached exceptional ui state */
+static uiexception_type_t uiexception_type = UIEXCEPTION_TYPE_NONE;
+
 /** Cached PID of process owning the topmost window on UI */
 static int topmost_window_pid = -1;
 
@@ -1545,8 +1570,7 @@ static gpointer mdy_datapipe_display_state_filter_cb(gpointer data)
 
     case MCE_DISPLAY_LPM_OFF:
     case MCE_DISPLAY_LPM_ON:
-        if( lipstick_service_state == SERVICE_STATE_RUNNING &&
-            mdy_use_low_power_mode && mdy_low_power_mode_supported )
+        if( mdy_lpm_allowed() )
             break;
 
         mce_log(LL_DEBUG, "reject low power mode display request");
@@ -1653,6 +1677,10 @@ static void mdy_datapipe_display_state_curr_cb(gconstpointer data)
     if( display_state_curr == prev )
         goto EXIT;
 
+    /* Entered (visible) LPM state -> schedule sanity check */
+    if( display_state_curr == MCE_DISPLAY_LPM_ON  )
+        mdy_lpm_schedule_sanitize();
+
     mdy_statistics_update();
     mdy_blanking_pause_evaluate_allowed();
     mdy_blanking_inhibit_schedule_broadcast();
@@ -1675,6 +1703,11 @@ static void mdy_datapipe_display_state_next_cb(gconstpointer data)
     if( display_state_next == prev )
         goto EXIT;
 
+    /* Leaving LPM state -> sanity check no longer needed */
+    if( display_state_next != MCE_DISPLAY_LPM_ON &&
+        display_state_next != MCE_DISPLAY_LPM_OFF )
+        mdy_lpm_cancel_sanitize();
+
     mdy_ui_dimming_rethink();
 
     /* Start/stop orientation sensor */
@@ -1835,9 +1868,6 @@ static void mdy_datapipe_charger_state_cb(gconstpointer data)
     return;
 }
 
-/** Cached exceptional ui state */
-static uiexception_type_t uiexception_type = UIEXCEPTION_TYPE_NONE;
-
 /** Handle uiexception_type_pipe notifications
  */
 static void mdy_datapipe_uiexception_type_cb(gconstpointer data)
@@ -2319,6 +2349,111 @@ static void mdy_fbdev_rethink(void)
         mce_fbdev_open();
 }
 
+/* ========================================================================= *
+ * LOW_POWER_MODE
+ * ========================================================================= */
+
+/** Predicate for: Entering LPM display states is allowed
+ *
+ * Entering LPM display states happens in co-operation between
+ * mce and lipstick, via asynchronous D-Bus IPC.
+ *
+ * There are some situations where we know that entering LPM
+ * just wont be possible - this function is used for detecting
+ * such situations and denying attempts globally already at
+ * display state request filtering stage.
+ *
+ * @see #mdy_datapipe_display_state_filter_cb()
+ *
+ * Additionally we can bump into situations where it looks like
+ * entering LPM is ok, but UI side does not make the necessary
+ * transitions - these are handled by starting a timer on entry
+ * to MCE_DISPLAY_LPM_ON and checking relevant state data after
+ * a brief delay (or cancelling the checkup upon leaving LPM).
+ *
+ * @see #mdy_datapipe_display_state_curr_cb()
+ * @see #mdy_datapipe_display_state_next_cb()
+ *
+ * @return true if entering LPM states is allowed, false otherwise
+ */
+static bool mdy_lpm_allowed(void)
+{
+    bool allowed = false;
+
+    /* Feature must be enabled and supported */
+    if( !mdy_use_low_power_mode || !mdy_low_power_mode_supported )
+        goto EXIT;
+
+    /* Lipstick must be running */
+    if( lipstick_service_state != SERVICE_STATE_RUNNING )
+        goto EXIT;
+
+    /* Since call and alarm UIs are layered above lockscreen,
+     * they are mutually exclusive with lpm */
+    if( uiexception_type & (UIEXCEPTION_TYPE_CALL |
+                            UIEXCEPTION_TYPE_ALARM) )
+        goto EXIT;
+
+    allowed = true;
+
+EXIT:
+    return allowed;
+}
+
+/** Timer id for: Sanity check after entering LPM state
+ */
+static guint mdy_lpm_sanitize_id = 0;
+
+/** Timer callback for: Sanity check after entering LPM state
+ *
+ * @param aptr unused user data pointer
+ *
+ * @return G_SOURCE_REMOVE (to stop timer from repeating)
+ */
+static gboolean mdy_lpm_sanitize_cb(gpointer aptr)
+{
+    (void)aptr;
+
+    mdy_lpm_sanitize_id = 0;
+
+    /* If we're still in LPM state, and something is on
+     * top of lockscreen -> we have dimmed out UI that
+     * can't be interacted with -> exit from LPM. */
+
+    if( display_state_next != MCE_DISPLAY_LPM_ON &&
+        display_state_next != MCE_DISPLAY_LPM_OFF )
+        goto EXIT;
+
+    if( topmost_window_pid == -1 )
+        goto EXIT;
+
+    mce_log(LL_WARN, "app on screen; exiting lpm state");
+    mce_datapipe_request_display_state(MCE_DISPLAY_OFF);
+
+EXIT:
+    return G_SOURCE_REMOVE;
+}
+
+/** Schedule sanity check for staying in LPM state
+ */
+static void mdy_lpm_schedule_sanitize(void)
+{
+    if( !mdy_lpm_sanitize_id ) {
+        mdy_lpm_sanitize_id =
+            g_timeout_add(LPM_SANITIZE_DELAY, mdy_lpm_sanitize_cb, 0);
+    }
+}
+
+/** Cancel scheduled LPM state sanity check
+ */
+static void mdy_lpm_cancel_sanitize(void)
+{
+    if( mdy_lpm_sanitize_id ) {
+        g_source_remove(mdy_lpm_sanitize_id),
+            mdy_lpm_sanitize_id = 0;
+    }
+}
+
 /* ========================================================================= *
  * HIGH_BRIGHTNESS_MODE
  * ========================================================================= */
@@ -11213,6 +11348,8 @@ void g_module_unload(GModule *module)
 
     mdy_poweron_led_rethink_cancel();
 
+    mdy_lpm_cancel_sanitize();
+
     /* Remove callbacks on module unload */
     mce_sensorfw_orient_set_notify(0);