Framebuffer: Support variable number of framebuffers in the UI

This change defines a macro NUM_FRAME_BUFFERS to set
the desired number of framebuffers to be used by the UI,
instead of hard-coding 2 framebuffers.

Aditional logic has been  added to handle the initialization
and destruction of NUM_FRAME_BUFFERS buffers.

Change-Id: I3a4bfec3e0f453432f2ffebf084c00f574d3be46
Signed-off-by: Rodrigo Obregon <robregon@ti.com>

Author: Rodrigo Obregon

include/ui/FramebufferNativeWindow.h

@@ -29,6 +29,7 @@
 
 #include <ui/egl/android_natives.h>
 
+#define NUM_FRAME_BUFFERS  2
 
 extern "C" EGLNativeWindowType android_createDisplaySurface(void);
 
@@ -69,7 +70,7 @@ class FramebufferNativeWindow
     framebuffer_device_t* fbDev;
     alloc_device_t* grDev;
 
-    sp<NativeBuffer> buffers[2];
+    sp<NativeBuffer> buffers[NUM_FRAME_BUFFERS];
     sp<NativeBuffer> front;
 
     mutable Mutex mutex;

libs/ui/FramebufferNativeWindow.cpp

@@ -82,6 +82,7 @@ FramebufferNativeWindow::FramebufferNativeWindow()
     if (hw_get_module(GRALLOC_HARDWARE_MODULE_ID, &module) == 0) {
         int stride;
         int err;
+        int i;
         err = framebuffer_open(module, &fbDev);
         LOGE_IF(err, "couldn't open framebuffer HAL (%s)", strerror(-err));
 
@@ -95,27 +96,33 @@ FramebufferNativeWindow::FramebufferNativeWindow()
         mUpdateOnDemand = (fbDev->setUpdateRect != 0);
 
         // initialize the buffer FIFO
-        mNumBuffers = 2;
-        mNumFreeBuffers = 2;
+        mNumBuffers = NUM_FRAME_BUFFERS;
+        mNumFreeBuffers = NUM_FRAME_BUFFERS;
         mBufferHead = mNumBuffers-1;
-        buffers[0] = new NativeBuffer(
-                fbDev->width, fbDev->height, fbDev->format, GRALLOC_USAGE_HW_FB);
-        buffers[1] = new NativeBuffer(
-                fbDev->width, fbDev->height, fbDev->format, GRALLOC_USAGE_HW_FB);
-        
-        err = grDev->alloc(grDev,
-                fbDev->width, fbDev->height, fbDev->format, 
-                GRALLOC_USAGE_HW_FB, &buffers[0]->handle, &buffers[0]->stride);
-
-        LOGE_IF(err, "fb buffer 0 allocation failed w=%d, h=%d, err=%s",
-                fbDev->width, fbDev->height, strerror(-err));
-
-        err = grDev->alloc(grDev,
-                fbDev->width, fbDev->height, fbDev->format, 
-                GRALLOC_USAGE_HW_FB, &buffers[1]->handle, &buffers[1]->stride);
 
-        LOGE_IF(err, "fb buffer 1 allocation failed w=%d, h=%d, err=%s",
-                fbDev->width, fbDev->height, strerror(-err));
+        for (i = 0; i < mNumBuffers; i++)
+        {
+                buffers[i] = new NativeBuffer(
+                        fbDev->width, fbDev->height, fbDev->format, GRALLOC_USAGE_HW_FB);
+        }
+
+        for (i = 0; i < mNumBuffers; i++)
+        {
+                err = grDev->alloc(grDev,
+                        fbDev->width, fbDev->height, fbDev->format,
+                        GRALLOC_USAGE_HW_FB, &buffers[i]->handle, &buffers[i]->stride);
+
+                LOGE_IF(err, "fb buffer %d allocation failed w=%d, h=%d, err=%s",
+                        i, fbDev->width, fbDev->height, strerror(-err));
+
+                if (err)
+                {
+                        mNumBuffers = i;
+                        mNumFreeBuffers = i;
+                        mBufferHead = mNumBuffers-1;
+                        break;
+                }
+        }
 
         const_cast<uint32_t&>(android_native_window_t::flags) = fbDev->flags; 
         const_cast<float&>(android_native_window_t::xdpi) = fbDev->xdpi;