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Commit 83806897 authored by Chia-I Wu's avatar Chia-I Wu
Browse files

surfaceflinger: fix fencing when layers become invisible 

A layer always holds on to a buffer (after the first one is
acquired).  When a new buffer comes in, and the layer is visible, it
will

 - acquire the new buffer
 - present the new buffer to HWC
 - get the release fence from HWC
 - associate the old buffer with the release fence and release it

But if the layer happens to be becoming invisible, it will go
through

 - acquire the new buffer
 - destroy the HWC layer and present
 - release the old buffer without any fence

The problem here is that the old buffer is still on screen until the
present takes effect (e.g., on next HW vsync).  Rendering artifacts
may be seen on screen.

This commit changes the acquire/release process for layer becoming
invisible to

 - acquire the new buffer
 - destroy the HWC layer and present
 - get a fence from HWC
 - associate the old buffer with the fence and release it

We do not require HWC getReleaseFences to return fences for
destroyed layers.  We can only use the next best fence, the present
fence.

Bug: 68490054
Test: manual
Change-Id: I68bbf392a6681c6512fc0be68a7d17df122f7308
parent 7957b72d

services/surfaceflinger/BufferLayer.cpp

+0 −3
Original line number Diff line number Diff line
@@ -262,9 +262,6 @@ void BufferLayer::onDraw(const RenderArea& renderArea, const Region& clip, 
}



void BufferLayer::onLayerDisplayed(const sp<Fence>& releaseFence) {

    if (mHwcLayers.empty()) {

        return;

    }

    mSurfaceFlingerConsumer->setReleaseFence(releaseFence);

}

services/surfaceflinger/DisplayDevice.cpp

+8 −0
Original line number Diff line number Diff line
@@ -325,6 +325,14 @@ const Vector< sp<Layer> >& DisplayDevice::getVisibleLayersSortedByZ() const { 
    return mVisibleLayersSortedByZ;

}



void DisplayDevice::setLayersNeedingFences(const Vector< sp<Layer> >& layers) {

    mLayersNeedingFences = layers;

}



const Vector< sp<Layer> >& DisplayDevice::getLayersNeedingFences() const {

    return mLayersNeedingFences;

}



Region DisplayDevice::getDirtyRegion(bool repaintEverything) const {

    Region dirty;

    if (repaintEverything) {

services/surfaceflinger/DisplayDevice.h

+4 −0
Original line number Diff line number Diff line
@@ -113,6 +113,8 @@ public: 


    void                    setVisibleLayersSortedByZ(const Vector< sp<Layer> >& layers);

    const Vector< sp<Layer> >& getVisibleLayersSortedByZ() const;

    void                    setLayersNeedingFences(const Vector< sp<Layer> >& layers);

    const Vector< sp<Layer> >& getLayersNeedingFences() const;

    Region                  getDirtyRegion(bool repaintEverything) const;



    void                    setLayerStack(uint32_t stack);
@@ -214,6 +216,8 @@ private: 


    // list of visible layers on that display

    Vector< sp<Layer> > mVisibleLayersSortedByZ;

    // list of layers needing fences

    Vector< sp<Layer> > mLayersNeedingFences;



    /*

     * Transaction state

services/surfaceflinger/Layer.cpp

+4 −2
Original line number Diff line number Diff line
@@ -217,9 +217,9 @@ bool Layer::createHwcLayer(HWComposer* hwc, int32_t hwcId) { 
    return true;

}



void Layer::destroyHwcLayer(int32_t hwcId) {

bool Layer::destroyHwcLayer(int32_t hwcId) {

    if (mHwcLayers.count(hwcId) == 0) {

        return;

        return false;

    }

    auto& hwcInfo = mHwcLayers[hwcId];

    LOG_ALWAYS_FATAL_IF(hwcInfo.layer == nullptr, "Attempt to destroy null layer");
@@ -228,6 +228,8 @@ void Layer::destroyHwcLayer(int32_t hwcId) { 
    // The layer destroyed listener should have cleared the entry from

    // mHwcLayers. Verify that.

    LOG_ALWAYS_FATAL_IF(mHwcLayers.count(hwcId) != 0, "Stale layer entry in mHwcLayers");



    return true;

}



void Layer::destroyAllHwcLayers() {

services/surfaceflinger/Layer.h

+1 −1
Original line number Diff line number Diff line
@@ -414,7 +414,7 @@ public: 
    // -----------------------------------------------------------------------



    bool createHwcLayer(HWComposer* hwc, int32_t hwcId);

    void destroyHwcLayer(int32_t hwcId);

    bool destroyHwcLayer(int32_t hwcId);

    void destroyAllHwcLayers();



    bool hasHwcLayer(int32_t hwcId) { return mHwcLayers.count(hwcId) > 0; }