log more info on fence sync_merge error

also fix a typo where the wrong value was passed to sterror.

Change-Id: I4df2abe582e14c8f816b65818f4593a6bd3c23ea

1 files changed, 4 insertions, 2 deletions

diff --git a/libs/ui/Fence.cpp b/libs/ui/Fence.cpp
index 932bcdd4ee..cec587613c 100644
--- a/libs/ui/Fence.cpp
+++ b/libs/ui/Fence.cpp
@@ -55,8 +55,10 @@ sp<Fence> Fence::merge(const String8& name, const sp<Fence>& f1,
     ATRACE_CALL();
     int result = sync_merge(name.string(), f1->mFenceFd, f2->mFenceFd);
     if (result == -1) {
-        ALOGE("merge: sync_merge returned an error: %s (%d)", strerror(-errno),
-                errno);
+        status_t err = -errno;
+        ALOGE("merge: sync_merge(\"%s\", %d, %d) returned an error: %s (%d)",
+                name.string(), f1->mFenceFd, f2->mFenceFd,
+                strerror(-err), err);
         return NO_FENCE;
     }
     return sp<Fence>(new Fence(result));