drm: clear buffer on creation for scanout DRM buffers (#51)

include/aquamarine/allocator/Allocator.hpp

@@ -14,11 +14,16 @@ namespace Aquamarine {
         bool                      scanout = false, cursor = false, multigpu = false;
     };
 
+    enum eAllocatorType {
+        AQ_ALLOCATOR_TYPE_GBM = 0,
+    };
+
     class IAllocator {
       public:
         virtual ~IAllocator()                                                                                                                                      = default;
         virtual Hyprutils::Memory::CSharedPointer<IBuffer>  acquire(const SAllocatorBufferParams& params, Hyprutils::Memory::CSharedPointer<CSwapchain> swapchain) = 0;
         virtual Hyprutils::Memory::CSharedPointer<CBackend> getBackend()                                                                                           = 0;
         virtual int                                         drmFD()                                                                                                = 0;
+        virtual eAllocatorType                              type()                                                                                                 = 0;
     };
 };

include/aquamarine/allocator/GBM.hpp

@@ -45,6 +45,7 @@ namespace Aquamarine {
         virtual Hyprutils::Memory::CSharedPointer<IBuffer>      acquire(const SAllocatorBufferParams& params, Hyprutils::Memory::CSharedPointer<CSwapchain> swapchain_);
         virtual Hyprutils::Memory::CSharedPointer<CBackend>     getBackend();
         virtual int                                             drmFD();
+        virtual eAllocatorType                                  type();
 
         //
         Hyprutils::Memory::CWeakPointer<CGBMAllocator> self;

include/aquamarine/backend/DRM.hpp

@@ -374,11 +374,10 @@ namespace Aquamarine {
         Hyprutils::Memory::CSharedPointer<IDRMImplementation> impl;
         Hyprutils::Memory::CWeakPointer<CDRMBackend>          primary;
 
-        // multigpu state, only present if this backend is not primary, aka if this->primary != nullptr
         struct {
             Hyprutils::Memory::CSharedPointer<IAllocator>   allocator;
             Hyprutils::Memory::CSharedPointer<CDRMRenderer> renderer;
-        } mgpu;
+        } rendererState;
 
         Hyprutils::Memory::CWeakPointer<CBackend>                     backend;
 
@@ -415,5 +414,6 @@ namespace Aquamarine {
         friend class CDRMAtomicImpl;
         friend class CDRMAtomicRequest;
         friend class CDRMLease;
+        friend class CGBMBuffer;
     };
 };

src/allocator/GBM.cpp

@@ -1,11 +1,13 @@
 #include <aquamarine/allocator/GBM.hpp>
 #include <aquamarine/backend/Backend.hpp>
+#include <aquamarine/backend/DRM.hpp>
 #include <aquamarine/allocator/Swapchain.hpp>
 #include "FormatUtils.hpp"
 #include "Shared.hpp"
 #include <xf86drm.h>
 #include <gbm.h>
 #include <unistd.h>
+#include "../backend/drm/Renderer.hpp"
 
 using namespace Aquamarine;
 using namespace Hyprutils::Memory;
@@ -186,6 +188,12 @@ Aquamarine::CGBMBuffer::CGBMBuffer(const SAllocatorBufferParams& params, Hypruti
                                         modName ? modName : "Unknown"));
 
     free(modName);
+
+    if (params.scanout && swapchain->backendImpl->type() == AQ_BACKEND_DRM) {
+        // clear the buffer using the DRM renderer to avoid uninitialized mem
+        auto impl = (CDRMBackend*)swapchain->backendImpl.get();
+        impl->rendererState.renderer->clearBuffer(this);
+    }
 }
 
 Aquamarine::CGBMBuffer::~CGBMBuffer() {
@@ -305,3 +313,7 @@ Hyprutils::Memory::CSharedPointer<CBackend> Aquamarine::CGBMAllocator::getBacken
 int Aquamarine::CGBMAllocator::drmFD() {
     return fd;
 }
+
+eAllocatorType Aquamarine::CGBMAllocator::type() {
+    return AQ_ALLOCATOR_TYPE_GBM;
+}

src/backend/drm/DRM.cpp

@@ -493,27 +493,30 @@ bool Aquamarine::CDRMBackend::shouldBlit() {
 }
 
 bool Aquamarine::CDRMBackend::initMgpu() {
-    if (!primary)
+    SP<CGBMAllocator> newAllocator;
-        return true;
+    if (primary || backend->primaryAllocator->type() != AQ_ALLOCATOR_TYPE_GBM) {
+        newAllocator            = CGBMAllocator::create(backend->reopenDRMNode(gpu->fd), backend);
+        rendererState.allocator = newAllocator;
+    } else {
+        newAllocator            = ((CGBMAllocator*)backend->primaryAllocator.get())->self.lock();
+        rendererState.allocator = newAllocator;
+    }
 
-    auto newAllocator = CGBMAllocator::create(backend->reopenDRMNode(gpu->fd), backend);
+    if (!rendererState.allocator) {
-    mgpu.allocator    = newAllocator;
-
-    if (!mgpu.allocator) {
         backend->log(AQ_LOG_ERROR, "drm: initMgpu: no allocator");
         return false;
     }
 
-    mgpu.renderer = CDRMRenderer::attempt(newAllocator, backend.lock());
+    rendererState.renderer = CDRMRenderer::attempt(newAllocator, backend.lock());
 
-    if (!mgpu.renderer) {
+    if (!rendererState.renderer) {
         backend->log(AQ_LOG_ERROR, "drm: initMgpu: no renderer");
         return false;
     }
 
-    mgpu.renderer->self = mgpu.renderer;
+    rendererState.renderer->self = rendererState.renderer;
 
-    buildGlFormats(mgpu.renderer->formats);
+    buildGlFormats(rendererState.renderer->formats);
 
     return true;
 }
@@ -1463,7 +1466,7 @@ bool Aquamarine::CDRMOutput::commitState(bool onlyTest) {
 
             if (!mgpu.swapchain) {
                 TRACE(backend->backend->log(AQ_LOG_TRACE, "drm: No swapchain for blit, creating"));
-                mgpu.swapchain = CSwapchain::create(backend->mgpu.allocator, backend.lock());
+                mgpu.swapchain = CSwapchain::create(backend->rendererState.allocator, backend.lock());
             }
 
             auto OPTIONS = swapchain->currentOptions();
@@ -1480,8 +1483,8 @@ bool Aquamarine::CDRMOutput::commitState(bool onlyTest) {
             }
 
             auto NEWAQBUF   = mgpu.swapchain->next(nullptr);
-            auto blitResult = backend->mgpu.renderer->blit(STATE.buffer, NEWAQBUF,
+            auto blitResult = backend->rendererState.renderer->blit(
-                                                           (COMMITTED & COutputState::eOutputStateProperties::AQ_OUTPUT_STATE_EXPLICIT_IN_FENCE) ? STATE.explicitInFence : -1);
+                STATE.buffer, NEWAQBUF, (COMMITTED & COutputState::eOutputStateProperties::AQ_OUTPUT_STATE_EXPLICIT_IN_FENCE) ? STATE.explicitInFence : -1);
             if (!blitResult.success) {
                 backend->backend->log(AQ_LOG_ERROR, "drm: Backend requires blit, but blit failed");
                 return false;
@@ -1623,7 +1626,7 @@ bool Aquamarine::CDRMOutput::setCursor(SP<IBuffer> buffer, const Vector2D& hotsp
 
             if (!mgpu.cursorSwapchain) {
                 TRACE(backend->backend->log(AQ_LOG_TRACE, "drm: No cursorSwapchain for blit, creating"));
-                mgpu.cursorSwapchain = CSwapchain::create(backend->mgpu.allocator, backend.lock());
+                mgpu.cursorSwapchain = CSwapchain::create(backend->rendererState.allocator, backend.lock());
             }
 
             auto OPTIONS     = mgpu.cursorSwapchain->currentOptions();
@@ -1640,7 +1643,7 @@ bool Aquamarine::CDRMOutput::setCursor(SP<IBuffer> buffer, const Vector2D& hotsp
             }
 
             auto NEWAQBUF = mgpu.cursorSwapchain->next(nullptr);
-            if (!backend->mgpu.renderer->blit(buffer, NEWAQBUF).success) {
+            if (!backend->rendererState.renderer->blit(buffer, NEWAQBUF).success) {
                 backend->backend->log(AQ_LOG_ERROR, "drm: Backend requires blit, but cursor blit failed");
                 return false;
             }

src/backend/drm/Renderer.cpp

@@ -561,6 +561,52 @@ int CDRMRenderer::recreateBlitSync() {
     return fd;
 }
 
+void CDRMRenderer::clearBuffer(IBuffer* buf) {
+    setEGL();
+
+    auto   dmabuf = buf->dmabuf();
+    GLuint rboID = 0, fboID = 0;
+
+    if (!dmabuf.success) {
+        backend->log(AQ_LOG_ERROR, "EGL (clear): cannot clear a non-dmabuf");
+        return;
+    }
+
+    auto rboImage = createEGLImage(dmabuf);
+    if (rboImage == EGL_NO_IMAGE_KHR) {
+        backend->log(AQ_LOG_ERROR, std::format("EGL (clear): createEGLImage failed: {}", eglGetError()));
+        return;
+    }
+
+    GLCALL(glGenRenderbuffers(1, &rboID));
+    GLCALL(glBindRenderbuffer(GL_RENDERBUFFER, rboID));
+    GLCALL(egl.glEGLImageTargetRenderbufferStorageOES(GL_RENDERBUFFER, (GLeglImageOES)rboImage));
+    GLCALL(glBindRenderbuffer(GL_RENDERBUFFER, 0));
+
+    GLCALL(glGenFramebuffers(1, &fboID));
+    GLCALL(glBindFramebuffer(GL_FRAMEBUFFER, fboID));
+    GLCALL(glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, rboID));
+
+    GLCALL(glBindRenderbuffer(GL_RENDERBUFFER, rboID));
+    GLCALL(glBindFramebuffer(GL_FRAMEBUFFER, fboID));
+
+    TRACE(backend->log(AQ_LOG_TRACE, std::format("EGL (clear): fbo {} rbo {}", fboID, rboID)));
+
+    glClearColor(0.F, 0.F, 0.F, 1.F);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    glFlush();
+
+    GLCALL(glBindFramebuffer(GL_FRAMEBUFFER, 0));
+    GLCALL(glBindRenderbuffer(GL_RENDERBUFFER, 0));
+
+    glDeleteFramebuffers(1, &fboID);
+    glDeleteRenderbuffers(1, &rboID);
+    egl.eglDestroyImageKHR(egl.display, rboImage);
+
+    restoreEGL();
+}
+
 CDRMRenderer::SBlitResult CDRMRenderer::blit(SP<IBuffer> from, SP<IBuffer> to, int waitFD) {
     setEGL();
 

src/backend/drm/Renderer.hpp

@@ -53,11 +53,13 @@ namespace Aquamarine {
         };
 
         SBlitResult blit(Hyprutils::Memory::CSharedPointer<IBuffer> from, Hyprutils::Memory::CSharedPointer<IBuffer> to, int waitFD = -1);
+        // can't be a SP<> because we call it from buf's ctor...
+        void clearBuffer(IBuffer* buf);
 
-        void        setEGL();
+        void setEGL();
-        void        restoreEGL();
+        void restoreEGL();
 
-        void        onBufferAttachmentDrop(CDRMRendererBufferAttachment* attachment);
+        void onBufferAttachmentDrop(CDRMRendererBufferAttachment* attachment);
 
         struct {
             struct SShader {