Don't enable HDCP again if it is active

BUG=412841

Review URL: https://codereview.chromium.org/584533002

Cr-Commit-Position: refs/heads/master@{#296421}

ui/display/chromeos/display_configurator.cc

@@ -251,12 +251,22 @@ bool DisplayConfigurator::ApplyProtections(const ContentProtections& requests) {
       case DISPLAY_CONNECTION_TYPE_DISPLAYPORT:
       case DISPLAY_CONNECTION_TYPE_DVI:
       case DISPLAY_CONNECTION_TYPE_HDMI: {
-        HDCPState new_desired_state =
-            (all_desired & CONTENT_PROTECTION_METHOD_HDCP) ?
-                HDCP_STATE_DESIRED : HDCP_STATE_UNDESIRED;
-        if (!native_display_delegate_->SetHDCPState(*it->display,
-                                                    new_desired_state))
+        HDCPState current_state;
+        // Need to poll the driver for updates since other applications may
+        // have updated the state.
+        if (!native_display_delegate_->GetHDCPState(*it->display,
+                                                    &current_state))
           return false;
+        bool current_desired = (current_state != HDCP_STATE_UNDESIRED);
+        bool new_desired = (all_desired & CONTENT_PROTECTION_METHOD_HDCP);
+        // Don't enable again if HDCP is already active. Some buggy drivers
+        // may disable and enable if setting "desired" in active state.
+        if (current_desired != new_desired) {
+          HDCPState new_state =
+              new_desired ? HDCP_STATE_DESIRED : HDCP_STATE_UNDESIRED;
+          if (!native_display_delegate_->SetHDCPState(*it->display, new_state))
+            return false;
+        }
         break;
       }
       case DISPLAY_CONNECTION_TYPE_INTERNAL:

ui/display/chromeos/display_configurator_unittest.cc

@@ -1177,14 +1177,43 @@ TEST_F(DisplayConfiguratorTest, ContentProtectionTwoClients) {
   // Protections will be disabled only if no more clients request them.
   EXPECT_TRUE(configurator_.EnableContentProtection(
       client2, outputs_[1].display_id(), CONTENT_PROTECTION_METHOD_NONE));
-  EXPECT_EQ(GetSetHDCPStateAction(outputs_[1], HDCP_STATE_DESIRED).c_str(),
-            log_->GetActionsAndClear());
+  EXPECT_EQ(kNoActions, log_->GetActionsAndClear());
   EXPECT_TRUE(configurator_.EnableContentProtection(
       client1, outputs_[1].display_id(), CONTENT_PROTECTION_METHOD_NONE));
   EXPECT_EQ(GetSetHDCPStateAction(outputs_[1], HDCP_STATE_UNDESIRED).c_str(),
             log_->GetActionsAndClear());
 }
 
+TEST_F(DisplayConfiguratorTest, ContentProtectionTwoClientsEnable) {
+  DisplayConfigurator::ContentProtectionClientId client1 =
+      configurator_.RegisterContentProtectionClient();
+  DisplayConfigurator::ContentProtectionClientId client2 =
+      configurator_.RegisterContentProtectionClient();
+  EXPECT_NE(client1, client2);
+
+  configurator_.Init(false);
+  configurator_.ForceInitialConfigure(0);
+  UpdateOutputs(2, true);
+  log_->GetActionsAndClear();
+
+  // Only enable once if HDCP is enabling.
+  EXPECT_TRUE(configurator_.EnableContentProtection(
+      client1, outputs_[1].display_id(), CONTENT_PROTECTION_METHOD_HDCP));
+  native_display_delegate_->set_hdcp_state(HDCP_STATE_DESIRED);
+  EXPECT_TRUE(configurator_.EnableContentProtection(
+      client2, outputs_[1].display_id(), CONTENT_PROTECTION_METHOD_HDCP));
+  EXPECT_EQ(GetSetHDCPStateAction(outputs_[1], HDCP_STATE_DESIRED).c_str(),
+            log_->GetActionsAndClear());
+  native_display_delegate_->set_hdcp_state(HDCP_STATE_ENABLED);
+
+  // Don't enable again if HDCP is already active.
+  EXPECT_TRUE(configurator_.EnableContentProtection(
+      client1, outputs_[1].display_id(), CONTENT_PROTECTION_METHOD_HDCP));
+  EXPECT_TRUE(configurator_.EnableContentProtection(
+      client2, outputs_[1].display_id(), CONTENT_PROTECTION_METHOD_HDCP));
+  EXPECT_EQ(kNoActions, log_->GetActionsAndClear());
+}
+
 TEST_F(DisplayConfiguratorTest, HandleConfigureCrtcFailure) {
   InitWithSingleOutput();