commit 439afadf859e15f01cb2781949d2402e69e4b4b7
author Brian Lindahl <blindahl@google.com> Mon Nov 14 11:16:55 2022 -0700
committer Brian Lindahl <blindahl@google.com> Fri Dec 09 12:06:58 2022 -0700
tree c0dcca7383ebe2e2e58678e7e2ff88f99244677c
parent 0cbe46547ecbb237101d0d27c6bdb7761254b268

Push HWC cache slot generation down into CompositionEngine

Stop caching buffers inside SurfaceFlinger and remove the tight coupling
between SurfaceFlinger's ClientCache and the Hardware Composer cache.
This allows a better seperation of responsibility, where buffer cache
management is not split between HwcSlotGenerator and HwcBufferCache, but
is instead solely handled by HwcBufferCache.

Note that FramebufferSurface and VirtualDisplaySurface no longer use
HwcBufferCache, but instead use their own cache slot management that
is solely based on BufferQueue slot numbers.

Also do minor refactoring in FramebufferSurface to simplify code.

Bug: 258196272
Test: started and stopped multiple YouTube videos on adt4 and verified
no change in graphic buffer usage
Test: atest HwcBufferCacheTest
Test: atest OutputPrepareTest

Change-Id: Ica7955ab4bc70e3c70207390e36dff73a2fc4949

services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp

diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
index eb14933..ce602a8 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
@@ -72,6 +72,10 @@
     mConsumer->setDefaultBufferSize(limitedSize.width, limitedSize.height);
     mConsumer->setMaxAcquiredBufferCount(
             SurfaceFlinger::maxFrameBufferAcquiredBuffers - 1);
+
+    for (size_t i = 0; i < sizeof(mHwcBufferIds) / sizeof(mHwcBufferIds[0]); ++i) {
+        mHwcBufferIds[i] = UINT64_MAX;
+    }
 }
 
 void FramebufferSurface::resizeBuffers(const ui::Size& newSize) {
@@ -88,31 +92,16 @@
 }
 
 status_t FramebufferSurface::advanceFrame() {
-    uint32_t slot = 0;
-    sp<GraphicBuffer> buf;
-    sp<Fence> acquireFence(Fence::NO_FENCE);
-    Dataspace dataspace = Dataspace::UNKNOWN;
-    status_t result = nextBuffer(slot, buf, acquireFence, dataspace);
-    mDataSpace = dataspace;
-    if (result != NO_ERROR) {
-        ALOGE("error latching next FramebufferSurface buffer: %s (%d)",
-                strerror(-result), result);
-    }
-    return result;
-}
-
-status_t FramebufferSurface::nextBuffer(uint32_t& outSlot,
-        sp<GraphicBuffer>& outBuffer, sp<Fence>& outFence,
-        Dataspace& outDataspace) {
     Mutex::Autolock lock(mMutex);
 
     BufferItem item;
     status_t err = acquireBufferLocked(&item, 0);
     if (err == BufferQueue::NO_BUFFER_AVAILABLE) {
-        mHwcBufferCache.getHwcBuffer(mCurrentBufferSlot, mCurrentBuffer, &outSlot, &outBuffer);
+        mDataspace = Dataspace::UNKNOWN;
         return NO_ERROR;
     } else if (err != NO_ERROR) {
         ALOGE("error acquiring buffer: %s (%d)", strerror(-err), err);
+        mDataspace = Dataspace::UNKNOWN;
         return err;
     }
 
@@ -133,13 +122,18 @@
     mCurrentBufferSlot = item.mSlot;
     mCurrentBuffer = mSlots[mCurrentBufferSlot].mGraphicBuffer;
     mCurrentFence = item.mFence;
+    mDataspace = static_cast<Dataspace>(item.mDataSpace);
 
-    outFence = item.mFence;
-    mHwcBufferCache.getHwcBuffer(mCurrentBufferSlot, mCurrentBuffer, &outSlot, &outBuffer);
-    outDataspace = static_cast<Dataspace>(item.mDataSpace);
-    status_t result = mHwc.setClientTarget(mDisplayId, outSlot, outFence, outBuffer, outDataspace);
+    // assume HWC has previously seen the buffer in this slot
+    sp<GraphicBuffer> hwcBuffer = sp<GraphicBuffer>(nullptr);
+    if (mCurrentBuffer->getId() != mHwcBufferIds[mCurrentBufferSlot]) {
+        mHwcBufferIds[mCurrentBufferSlot] = mCurrentBuffer->getId();
+        hwcBuffer = mCurrentBuffer; // HWC hasn't previously seen this buffer in this slot
+    }
+    status_t result = mHwc.setClientTarget(mDisplayId, mCurrentBufferSlot, mCurrentFence, hwcBuffer,
+                                           mDataspace);
     if (result != NO_ERROR) {
-        ALOGE("error posting framebuffer: %d", result);
+        ALOGE("error posting framebuffer: %s (%d)", strerror(-result), result);
         return result;
     }
 
@@ -190,7 +184,7 @@
         limitedSize.width = maxSize.height * aspectRatio;
         wasLimited = true;
     }
-    ALOGI_IF(wasLimited, "framebuffer size has been limited to [%dx%d] from [%dx%d]",
+    ALOGI_IF(wasLimited, "Framebuffer size has been limited to [%dx%d] from [%dx%d]",
              limitedSize.width, limitedSize.height, size.width, size.height);
     return limitedSize;
 }
@@ -198,9 +192,9 @@
 void FramebufferSurface::dumpAsString(String8& result) const {
     Mutex::Autolock lock(mMutex);
     result.append("   FramebufferSurface\n");
-    result.appendFormat("      mDataSpace=%s (%d)\n",
-                        dataspaceDetails(static_cast<android_dataspace>(mDataSpace)).c_str(),
-                        mDataSpace);
+    result.appendFormat("      mDataspace=%s (%d)\n",
+                        dataspaceDetails(static_cast<android_dataspace>(mDataspace)).c_str(),
+                        mDataspace);
     ConsumerBase::dumpLocked(result, "      ");
 }