commit 4d407a0f05ad9ba3c232ff5b6742495660c0e4ab
author Jesse Hall <jessehall@google.com> Mon Aug 25 14:44:16 2014 -0700
committer Jesse Hall <jessehall@google.com> Mon Aug 25 16:05:01 2014 -0700
tree 6e6996b8f1378b6034790f5fda73a3e22968ce36
parent f00945cfd7b105ad83aa0e26478681ee2ebf9bb7

surfaceflinger: Trace HW vsync enable

This makes it possible to tell whether two HW vsync signals are too
far apart because one was late, or because we turned HW vsync off
briefly between them.

Bug: 17259382
Change-Id: If4fba2a8a6013568349949ce87c5c36f0468d2a2

services/surfaceflinger/DisplayHardware/HWComposer.cpp

diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index a8dcf98..6302053 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -524,6 +524,10 @@
             if (!err) {
                 int32_t& events(mDisplayData[disp].events);
                 events = (events & ~eventBit) | newValue;
+
+                char tag[16];
+                snprintf(tag, sizeof(tag), "HW_VSYNC_ON_%1u", disp);
+                ATRACE_INT(tag, enabled);
             }
         }
         // error here should not happen -- not sure what we should