Force HALs to explicitly enable legacy method for clearing buffer caches

Some HAL implementations can't support setLayerBuffer multiple times to
clear the per-layer buffer caches. Therefore, default this behavior to
disabled, and allow HALs to explcitily enable this behavior to obtain
the necessary memory savings.

Test: play videos with both true and false on both HIDL and AIDL
Bug: 285561686
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f70d9c4528888134e16003470b76dd1e81b8631d)
Merged-In: I928cef25e35cfc5337db4ceb8581bf5926b4fbe3
Change-Id: I928cef25e35cfc5337db4ceb8581bf5926b4fbe3

7 files changed, 55 insertions, 16 deletions

diff --git a/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp b/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp
index f7049b98e7..c0eb36dc02 100644
--- a/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp
@@ -20,6 +20,7 @@
 
 #include "AidlComposerHal.h"
 
+#include <SurfaceFlingerProperties.h>
 #include <android-base/file.h>
 #include <android/binder_ibinder_platform.h>
 #include <android/binder_manager.h>
@@ -249,15 +250,18 @@ AidlComposer::AidlComposer(const std::string& serviceName) {
         ALOGE("getInterfaceVersion for AidlComposer constructor failed %s",
               status.getDescription().c_str());
     }
-    if (version == 1) {
-        mClearSlotBuffer = sp<GraphicBuffer>::make(1, 1, PIXEL_FORMAT_RGBX_8888,
-                                                   GraphicBuffer::USAGE_HW_COMPOSER |
-                                                           GraphicBuffer::USAGE_SW_READ_OFTEN |
-                                                           GraphicBuffer::USAGE_SW_WRITE_OFTEN,
-                                                   "AidlComposer");
-        if (!mClearSlotBuffer || mClearSlotBuffer->initCheck() != ::android::OK) {
-            LOG_ALWAYS_FATAL("Failed to allocate a buffer for clearing layer buffer slots");
-            return;
+    mSupportsBufferSlotsToClear = version > 1;
+    if (!mSupportsBufferSlotsToClear) {
+        if (sysprop::clear_slots_with_set_layer_buffer(false)) {
+            mClearSlotBuffer = sp<GraphicBuffer>::make(1, 1, PIXEL_FORMAT_RGBX_8888,
+                                                       GraphicBuffer::USAGE_HW_COMPOSER |
+                                                               GraphicBuffer::USAGE_SW_READ_OFTEN |
+                                                               GraphicBuffer::USAGE_SW_WRITE_OFTEN,
+                                                       "AidlComposer");
+            if (!mClearSlotBuffer || mClearSlotBuffer->initCheck() != ::android::OK) {
+                LOG_ALWAYS_FATAL("Failed to allocate a buffer for clearing layer buffer slots");
+                return;
+            }
         }
     }
 
@@ -844,12 +848,12 @@ Error AidlComposer::setLayerBufferSlotsToClear(Display display, Layer layer,
     Error error = Error::NONE;
     mMutex.lock_shared();
     if (auto writer = getWriter(display)) {
-        // Backwards compatible way of clearing buffer is to set the layer buffer with a placeholder
-        // buffer, using the slot that needs to cleared... tricky.
-        if (mClearSlotBuffer == nullptr) {
+        if (mSupportsBufferSlotsToClear) {
             writer->get().setLayerBufferSlotsToClear(translate<int64_t>(display),
                                                      translate<int64_t>(layer), slotsToClear);
-        } else {
+            // Backwards compatible way of clearing buffer slots is to set the layer buffer with a
+            // placeholder buffer, using the slot that needs to cleared... tricky.
+        } else if (mClearSlotBuffer != nullptr) {
             for (uint32_t slot : slotsToClear) {
                 // Don't clear the active buffer slot because we need to restore the active buffer
                 // after clearing the requested buffer slots with a placeholder buffer.
diff --git a/services/surfaceflinger/DisplayHardware/AidlComposerHal.h b/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
index ce05b382cc..b8ae26f879 100644
--- a/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
@@ -284,6 +284,8 @@ private:
     // threading annotations.
     ftl::SharedMutex mMutex;
 
+    // Whether or not explicitly clearing buffer slots is supported.
+    bool mSupportsBufferSlotsToClear;
     // Buffer slots for layers are cleared by setting the slot buffer to this buffer.
     sp<GraphicBuffer> mClearSlotBuffer;
 
diff --git a/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp b/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp
index e0f6c45f70..9b41da5754 100644
--- a/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp
@@ -24,12 +24,14 @@
 
 #include "HidlComposerHal.h"
 
+#include <SurfaceFlingerProperties.h>
 #include <android/binder_manager.h>
 #include <composer-command-buffer/2.2/ComposerCommandBuffer.h>
 #include <hidl/HidlTransportSupport.h>
 #include <hidl/HidlTransportUtils.h>
 #include <log/log.h>
 #include <utils/Trace.h>
+
 #include "HWC2.h"
 #include "Hal.h"
 
@@ -189,6 +191,9 @@ std::vector<To> translate(const hidl_vec<From>& in) {
 }
 
 sp<GraphicBuffer> allocateClearSlotBuffer() {
+    if (!sysprop::clear_slots_with_set_layer_buffer(false)) {
+        return nullptr;
+    }
     sp<GraphicBuffer> buffer = sp<GraphicBuffer>::make(1, 1, PIXEL_FORMAT_RGBX_8888,
                                                        GraphicBuffer::USAGE_HW_COMPOSER |
                                                                GraphicBuffer::USAGE_SW_READ_OFTEN |
@@ -246,7 +251,7 @@ HidlComposer::HidlComposer(const std::string& serviceName)
         LOG_ALWAYS_FATAL("failed to create composer client");
     }
 
-    if (!mClearSlotBuffer) {
+    if (!mClearSlotBuffer && sysprop::clear_slots_with_set_layer_buffer(false)) {
         LOG_ALWAYS_FATAL("Failed to allocate a buffer for clearing layer buffer slots");
         return;
     }
@@ -716,7 +721,11 @@ Error HidlComposer::setLayerBufferSlotsToClear(Display display, Layer layer,
     if (slotsToClear.empty()) {
         return Error::NONE;
     }
-    // Backwards compatible way of clearing buffer is to set the layer buffer with a placeholder
+    // This can be null when the HAL hasn't explicitly enabled this feature.
+    if (mClearSlotBuffer == nullptr) {
+        return Error::NONE;
+    }
+    //  Backwards compatible way of clearing buffer is to set the layer buffer with a placeholder
     // buffer, using the slot that needs to cleared... tricky.
     for (uint32_t slot : slotsToClear) {
         // Don't clear the active buffer slot because we need to restore the active buffer after
diff --git a/services/surfaceflinger/SurfaceFlingerProperties.cpp b/services/surfaceflinger/SurfaceFlingerProperties.cpp
index 20fa091730..96c8b54005 100644
--- a/services/surfaceflinger/SurfaceFlingerProperties.cpp
+++ b/services/surfaceflinger/SurfaceFlingerProperties.cpp
@@ -375,5 +375,9 @@ bool ignore_hdr_camera_layers(bool defaultValue) {
     return SurfaceFlingerProperties::ignore_hdr_camera_layers().value_or(defaultValue);
 }
 
+bool clear_slots_with_set_layer_buffer(bool defaultValue) {
+    return SurfaceFlingerProperties::clear_slots_with_set_layer_buffer().value_or(defaultValue);
+}
+
 } // namespace sysprop
 } // namespace android
diff --git a/services/surfaceflinger/SurfaceFlingerProperties.h b/services/surfaceflinger/SurfaceFlingerProperties.h
index 080feee686..951f8f8cb3 100644
--- a/services/surfaceflinger/SurfaceFlingerProperties.h
+++ b/services/surfaceflinger/SurfaceFlingerProperties.h
@@ -102,6 +102,8 @@ bool enable_sdr_dimming(bool defaultValue);
 
 bool ignore_hdr_camera_layers(bool defaultValue);
 
+bool clear_slots_with_set_layer_buffer(bool defaultValue);
+
 } // namespace sysprop
 } // namespace android
 #endif // SURFACEFLINGERPROPERTIES_H_
diff --git a/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop b/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop
index bcbe21a483..689f51ad5b 100644
--- a/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop
+++ b/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop
@@ -470,4 +470,18 @@ prop {
     scope: Public
     access: Readonly
     prop_name: "ro.surface_flinger.ignore_hdr_camera_layers"
-}
\ No newline at end of file
+}
+
+# When enabled, SurfaceFlinger will attempt to clear the per-layer HAL buffer cache slots for
+# buffers when they are evicted from the app cache by using additional setLayerBuffer commands.
+# Ideally, this behavior would always be enabled to reduce graphics memory consumption. However,
+# Some HAL implementations may not support the additional setLayerBuffer commands used to clear
+# the cache slots.
+prop {
+    api_name: "clear_slots_with_set_layer_buffer"
+    type: Boolean
+    scope: Public
+    access: Readonly
+    prop_name: "ro.surface_flinger.clear_slots_with_set_layer_buffer"
+}
+
diff --git a/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt b/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt
index 348a462038..9660ff3de6 100644
--- a/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt
+++ b/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt
@@ -1,6 +1,10 @@
 props {
   module: "android.sysprop.SurfaceFlingerProperties"
   prop {
+    api_name: "clear_slots_with_set_layer_buffer"
+    prop_name: "ro.surface_flinger.clear_slots_with_set_layer_buffer"
+  }
+  prop {
     api_name: "color_space_agnostic_dataspace"
     type: Long
     prop_name: "ro.surface_flinger.color_space_agnostic_dataspace"