Don't start an observer without an extcon device

This prevents needless logspam at startup.

Bug: 123906489
Change-Id: Ib97b2a6a9aed3a681f48943c57bae4b5953fb54c
Test: m services.core
(cherry picked from commit 4ea6290b11d91a9110e63dc3f00041029c118e07)

2 files changed, 14 insertions, 3 deletions

diff --git a/services/core/java/com/android/server/ExtconUEventObserver.java b/services/core/java/com/android/server/ExtconUEventObserver.java
index 6b42b3d06d4b..5bd27c4dd481 100644
--- a/services/core/java/com/android/server/ExtconUEventObserver.java
+++ b/services/core/java/com/android/server/ExtconUEventObserver.java
@@ -159,7 +159,13 @@ public abstract class ExtconUEventObserver extends UEventObserver {
         }
     }
 
-    /** Does the {@link /sys/class/extcon} directory exist */
+    /** Does the {@code /sys/class/extcon/<name>} directory exist */
+    public static boolean namedExtconDirExists(String name) {
+        File extconDir = new File("/sys/class/extcon/" + name);
+        return extconDir.exists() && extconDir.isDirectory();
+    }
+
+    /** Does the {@code /sys/class/extcon} directory exist */
     public static boolean extconExists() {
         File extconDir = new File("/sys/class/extcon");
         return extconDir.exists() && extconDir.isDirectory();
diff --git a/services/core/java/com/android/server/policy/PhoneWindowManager.java b/services/core/java/com/android/server/policy/PhoneWindowManager.java
index d0ca861d8d3b..03d0e236b618 100644
--- a/services/core/java/com/android/server/policy/PhoneWindowManager.java
+++ b/services/core/java/com/android/server/policy/PhoneWindowManager.java
@@ -3556,11 +3556,15 @@ public class PhoneWindowManager implements WindowManagerPolicy {
                     }
                 }
             }
-        } else if (ExtconUEventObserver.extconExists()) {
+        } else if (ExtconUEventObserver.extconExists()
+                && ExtconUEventObserver.namedExtconDirExists(HdmiVideoExtconUEventObserver.NAME)) {
             HdmiVideoExtconUEventObserver observer = new HdmiVideoExtconUEventObserver();
             plugged = observer.init();
             mHDMIObserver = observer;
+        } else if (localLOGV) {
+            Slog.v(TAG, "Not observing HDMI plug state because HDMI was not found.");
         }
+
         // This dance forces the code in setHdmiPlugged to run.
         // Always do this so the sticky intent is stuck (to false) if there is no hdmi.
         mDefaultDisplayPolicy.setHdmiPlugged(plugged, true /* force */);
@@ -5616,7 +5620,8 @@ public class PhoneWindowManager implements WindowManagerPolicy {
 
     private class HdmiVideoExtconUEventObserver extends ExtconStateObserver<Boolean> {
         private static final String HDMI_EXIST = "HDMI=1";
-        private final ExtconInfo mHdmi = new ExtconInfo("hdmi");
+        private static final String NAME = "hdmi";
+        private final ExtconInfo mHdmi = new ExtconInfo(NAME);
 
         private boolean init() {
             boolean plugged = false;