SurfaceTexture: allow set_buffer_count(2)

This change relaxes an error check in SurfaceTexture::setBufferCount to
allow clients to explicitly set a buffer count of 2.  The clients that
will do this are camera and video decode.  Previously it was thought
that for those clients we would always use async mode, which requires a
minimum of 3 buffers.  However, we now believe that for some devices it
may make sense to use synchronous mode (with 2 buffers) to reduce memory
usage.

Bug: 5088418
Change-Id: I620a0ef75075745be9d6c8219e0246aaf33ba950

1 files changed, 5 insertions, 5 deletions

diff --git a/libs/gui/SurfaceTexture.cpp b/libs/gui/SurfaceTexture.cpp
index 16755ad..4f51f03 100644
--- a/libs/gui/SurfaceTexture.cpp
+++ b/libs/gui/SurfaceTexture.cpp
@@ -168,18 +168,18 @@ status_t SurfaceTexture::setBufferCount(int bufferCount) {
         }
     }
 
+    const int minBufferSlots = mSynchronousMode ?
+            MIN_SYNC_BUFFER_SLOTS : MIN_ASYNC_BUFFER_SLOTS;
     if (bufferCount == 0) {
-        const int minBufferSlots = mSynchronousMode ?
-                MIN_SYNC_BUFFER_SLOTS : MIN_ASYNC_BUFFER_SLOTS;
         mClientBufferCount = 0;
         bufferCount = (mServerBufferCount >= minBufferSlots) ?
                 mServerBufferCount : minBufferSlots;
         return setBufferCountServerLocked(bufferCount);
     }
 
-    // We don't allow the client to set a buffer-count less than
-    // MIN_ASYNC_BUFFER_SLOTS (3), there is no reason for it.
-    if (bufferCount < MIN_ASYNC_BUFFER_SLOTS) {
+    if (bufferCount < minBufferSlots) {
+        LOGE("setBufferCount: requested buffer count (%d) is less than "
+                "minimum (%d)", bufferCount, minBufferSlots);
         return BAD_VALUE;
     }