Initial implementation of EglGbmBackend

Uses EGL_MESA_platform_gbm to get an EglDisplay from a gbm_device.
The DrmBackend can provide a DrmBuffer for a gbm_surface and present
it.

Unfortunately buffer age seems to be slightly broken and we still have
artefacts.

CMakeLists.txt

@@ -164,6 +164,13 @@ if(Libdrm_FOUND AND UDEV_FOUND)
     set(HAVE_DRM TRUE)
 endif()
 
+find_package(gbm)
+set_package_properties(gbm PROPERTIES TYPE OPTIONAL PURPOSE "Required for egl ouput of drm backend.")
+set(HAVE_GBM FALSE)
+if(HAVE_DRM AND gbm_FOUND)
+    set(HAVE_GBM TRUE)
+endif()
+
 find_package(X11)
 set_package_properties(X11 PROPERTIES DESCRIPTION "X11 libraries"
                         URL "http://www.x.org"
@@ -448,6 +455,12 @@ if(HAVE_WAYLAND)
                 screens_drm.cpp
             )
     endif()
+    if(HAVE_GBM)
+        set(kwin_KDEINIT_SRCS
+                ${kwin_KDEINIT_SRCS}
+                egl_gbm_backend.cpp
+            )
+    endif()
 endif()
 
 if(UDEV_FOUND)
@@ -585,6 +598,10 @@ if(HAVE_DRM)
     set(kwinLibs ${kwinLibs} Libdrm::Libdrm)
 endif()
 
+if(HAVE_GBM)
+    set(kwinLibs ${kwinLibs} gbm::gbm)
+endif()
+
 add_library(kwin SHARED ${kwin_KDEINIT_SRCS})
 
 set_target_properties(kwin PROPERTIES

cmake/modules/Findgbm.cmake

+#.rst:
+# Findgbm
+# -------
+#
+# Try to find gbm on a Unix system.
+#
+# This will define the following variables:
+#
+# ``gbm_FOUND``
+#     True if (the requested version of) gbm is available
+# ``gbm_VERSION``
+#     The version of gbm
+# ``gbm_LIBRARIES``
+#     This can be passed to target_link_libraries() instead of the ``gbm::gbm``
+#     target
+# ``gbm_INCLUDE_DIRS``
+#     This should be passed to target_include_directories() if the target is not
+#     used for linking
+# ``gbm_DEFINITIONS``
+#     This should be passed to target_compile_options() if the target is not
+#     used for linking
+#
+# If ``gbm_FOUND`` is TRUE, it will also define the following imported target:
+#
+# ``gbm::gbm``
+#     The gbm library
+#
+# In general we recommend using the imported target, as it is easier to use.
+# Bear in mind, however, that if the target is in the link interface of an
+# exported library, it must be made available by the package config file.
+
+#=============================================================================
+# Copyright 2014 Alex Merry <alex.merry@kde.org>
+# Copyright 2014 Martin Gräßlin <mgraesslin@kde.org>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 3. The name of the author may not be used to endorse or promote products
+#    derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#=============================================================================
+
+if(CMAKE_VERSION VERSION_LESS 2.8.12)
+    message(FATAL_ERROR "CMake 2.8.12 is required by Findgbm.cmake")
+endif()
+if(CMAKE_MINIMUM_REQUIRED_VERSION VERSION_LESS 2.8.12)
+    message(AUTHOR_WARNING "Your project should require at least CMake 2.8.12 to use Findgbm.cmake")
+endif()
+
+if(NOT WIN32)
+    # Use pkg-config to get the directories and then use these values
+    # in the FIND_PATH() and FIND_LIBRARY() calls
+    find_package(PkgConfig)
+    pkg_check_modules(PKG_gbm QUIET gbm)
+
+    set(gbm_DEFINITIONS ${PKG_gbm_CFLAGS_OTHER})
+    set(gbm_VERSION ${PKG_gbm_VERSION})
+
+    find_path(gbm_INCLUDE_DIR
+        NAMES
+            gbm.h
+        HINTS
+            ${PKG_gbm_INCLUDE_DIRS}
+    )
+    find_library(gbm_LIBRARY
+        NAMES
+            gbm
+        HINTS
+            ${PKG_gbm_LIBRARY_DIRS}
+    )
+
+    include(FindPackageHandleStandardArgs)
+    find_package_handle_standard_args(gbm
+        FOUND_VAR
+            gbm_FOUND
+        REQUIRED_VARS
+            gbm_LIBRARY
+            gbm_INCLUDE_DIR
+        VERSION_VAR
+            gbm_VERSION
+    )
+
+    if(gbm_FOUND AND NOT TARGET gbm::gbm)
+        add_library(gbm::gbm UNKNOWN IMPORTED)
+        set_target_properties(gbm::gbm PROPERTIES
+            IMPORTED_LOCATION "${gbm_LIBRARY}"
+            INTERFACE_COMPILE_OPTIONS "${gbm_DEFINITIONS}"
+            INTERFACE_INCLUDE_DIRECTORIES "${gbm_INCLUDE_DIR}"
+        )
+    endif()
+
+    mark_as_advanced(gbm_LIBRARY gbm_INCLUDE_DIR)
+
+    # compatibility variables
+    set(gbm_LIBRARIES ${gbm_LIBRARY})
+    set(gbm_INCLUDE_DIRS ${gbm_INCLUDE_DIR})
+    set(gbm_VERSION_STRING ${gbm_VERSION})
+
+else()
+    message(STATUS "Findgbm.cmake cannot find gbm on Windows systems.")
+    set(gbm_FOUND FALSE)
+endif()
+
+include(FeatureSummary)
+set_package_properties(gbm PROPERTIES
+    URL "http://www.mesa3d.org"
+    DESCRIPTION "Mesa gbm library."
+)

config-kwin.h.cmake

@@ -16,6 +16,7 @@
 #cmakedefine01 HAVE_XCB_SYNC
 #cmakedefine01 HAVE_X11_XCB
 #cmakedefine01 HAVE_DRM
+#cmakedefine01 HAVE_GBM
 
 /* Define to 1 if you have the <unistd.h> header file. */
 #cmakedefine HAVE_UNISTD_H 1

drm_backend.cpp

@@ -25,6 +25,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "udev.h"
 #include "utils.h"
 #include "virtual_terminal.h"
+#if HAVE_GBM
+#include "egl_gbm_backend.h"
+#endif
 // Qt
 #include <QSocketNotifier>
 // system
@@ -34,6 +37,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <xf86drm.h>
 #include <xf86drmMode.h>
 #include <libdrm/drm_mode.h>
+#if HAVE_GBM
+#include <gbm.h>
+#endif
 
 #include <QDebug>
 
@@ -80,6 +86,12 @@ void DrmBackend::pageFlipHandler(int fd, unsigned int frame, unsigned int sec, u
     Q_UNUSED(usec)
     DrmBuffer *buffer = reinterpret_cast<DrmBuffer*>(data);
     buffer->m_backend->m_pageFlipPending = false;
+#if HAVE_GBM
+    if (buffer->m_bo) {
+        gbm_surface_release_buffer(buffer->m_surface, buffer->m_bo);
+        buffer->m_bo = nullptr;
+    }
+#endif
     Compositor::self()->bufferSwapComplete();
 }
 
@@ -186,11 +198,26 @@ QPainterBackend *DrmBackend::createQPainterBackend()
     return new DrmQPainterBackend(this);
 }
 
+OpenGLBackend *DrmBackend::createOpenGLBackend()
+{
+#if HAVE_GBM
+    return new EglGbmBackend(this);
+#endif
+    return AbstractBackend::createOpenGLBackend();
+}
+
 DrmBuffer *DrmBackend::createBuffer(const QSize &size)
 {
     return new DrmBuffer(this, size);
 }
 
+DrmBuffer *DrmBackend::createBuffer(gbm_surface *surface)
+{
+#if HAVE_GBM
+    return new DrmBuffer(this, surface);
+#endif
+}
+
 DrmBuffer::DrmBuffer(DrmBackend *backend, const QSize &size)
     : m_backend(backend)
     , m_size(size)
@@ -210,6 +237,34 @@ DrmBuffer::DrmBuffer(DrmBackend *backend, const QSize &size)
                  m_stride, createArgs.handle, &m_bufferId);
 }
 
+
+#if HAVE_GBM
+static void gbmCallback(gbm_bo *bo, void *data)
+{
+    Q_UNUSED(bo);
+    delete reinterpret_cast<DrmBuffer*>(data);
+}
+#endif
+
+DrmBuffer::DrmBuffer(DrmBackend *backend, gbm_surface *surface)
+    : m_backend(backend)
+    , m_surface(surface)
+{
+#if HAVE_GBM
+    m_bo = gbm_surface_lock_front_buffer(surface);
+    if (!m_bo) {
+        qWarning(KWIN_CORE) << "Locking front buffer failed";
+        return;
+    }
+    m_size = QSize(gbm_bo_get_width(m_bo), gbm_bo_get_height(m_bo));
+    m_stride = gbm_bo_get_stride(m_bo);
+    if (drmModeAddFB(m_backend->fd(), m_size.width(), m_size.height(), 24, 32, m_stride, gbm_bo_get_handle(m_bo).u32, &m_bufferId) != 0) {
+        qWarning(KWIN_CORE) << "drmModeAddFB failed";
+    }
+    gbm_bo_set_user_data(m_bo, this, gbmCallback);
+#endif
+}
+
 DrmBuffer::~DrmBuffer()
 {
     delete m_image;
@@ -224,6 +279,11 @@ DrmBuffer::~DrmBuffer()
         destroyArgs.handle = m_handle;
         drmIoctl(m_backend->fd(), DRM_IOCTL_MODE_DESTROY_DUMB, &destroyArgs);
     }
+#if HAVE_GBM
+    if (m_bo) {
+        gbm_surface_release_buffer(m_surface, m_bo);
+    }
+#endif
 }
 
 bool DrmBuffer::map()

drm_backend.h

@@ -25,6 +25,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QSize>
 #include <xf86drmMode.h>
 
+struct gbm_bo;
+struct gbm_surface;
+
 namespace KWin
 {
 
@@ -41,9 +44,11 @@ public:
 
     Screens *createScreens(QObject *parent = nullptr) override;
     QPainterBackend *createQPainterBackend() override;
+    OpenGLBackend* createOpenGLBackend() override;
 
     void init();
     DrmBuffer *createBuffer(const QSize &size);
+    DrmBuffer *createBuffer(gbm_surface *surface);
     void present(DrmBuffer *buffer);
 
     QSize size() const {
@@ -85,7 +90,10 @@ public:
 private:
     friend class DrmBackend;
     DrmBuffer(DrmBackend *backend, const QSize &size);
+    DrmBuffer(DrmBackend *backend, gbm_surface *surface);
     DrmBackend *m_backend;
+    gbm_surface *m_surface = nullptr;
+    gbm_bo *m_bo = nullptr;
     QSize m_size;
     quint32 m_handle = 0;
     quint32 m_bufferId = 0;

egl_gbm_backend.cpp

+/********************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (C) 2015 Martin Gräßlin <mgraesslin@kde.org>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*********************************************************************/
+#include "egl_gbm_backend.h"
+// kwin
+#include "composite.h"
+#include "drm_backend.h"
+#include "options.h"
+#include "screens.h"
+// kwin libs
+#include <kwinglplatform.h>
+// Qt
+#include <QOpenGLContext>
+// system
+#include <gbm.h>
+
+namespace KWin
+{
+
+EglGbmBackend::EglGbmBackend(DrmBackend *b)
+    : QObject(NULL)
+    , AbstractEglBackend()
+    , m_backend(b)
+{
+    initializeEgl();
+    init();
+    // Egl is always direct rendering
+    setIsDirectRendering(true);
+}
+
+EglGbmBackend::~EglGbmBackend()
+{
+    // TODO: cleanup front buffer?
+    cleanup();
+    if (m_gbmSurface) {
+        gbm_surface_destroy(m_gbmSurface);
+    }
+    if (m_device) {
+        gbm_device_destroy(m_device);
+    }
+}
+
+bool EglGbmBackend::initializeEgl()
+{
+    initClientExtensions();
+    EGLDisplay display = EGL_NO_DISPLAY;
+
+    // Use eglGetPlatformDisplayEXT() to get the display pointer
+    // if the implementation supports it.
+    if (!hasClientExtension(QByteArrayLiteral("EGL_EXT_platform_base")) ||
+            !hasClientExtension(QByteArrayLiteral("EGL_MESA_platform_gbm"))) {
+        setFailed("EGL_EXT_platform_base and/or EGL_MESA_platform_gbm missing");
+        return false;
+    }
+
+    m_device = gbm_create_device(m_backend->fd());
+    if (!m_device) {
+        setFailed("Could not create gbm device");
+        return false;
+    }
+
+    display = eglGetPlatformDisplayEXT(EGL_PLATFORM_GBM_MESA, m_device, nullptr);
+
+    if (display == EGL_NO_DISPLAY)
+        return false;
+    setEglDisplay(display);
+    return initEglAPI();
+}
+
+void EglGbmBackend::init()
+{
+    if (!initRenderingContext()) {
+        setFailed("Could not initialize rendering context");
+        return;
+    }
+
+    initKWinGL();
+    initBufferAge();
+    initWayland();
+}
+
+bool EglGbmBackend::initRenderingContext()
+{
+    initBufferConfigs();
+
+    EGLContext context = EGL_NO_CONTEXT;
+#ifdef KWIN_HAVE_OPENGLES
+    const EGLint context_attribs[] = {
+        EGL_CONTEXT_CLIENT_VERSION, 2,
+        EGL_NONE
+    };
+
+    context = eglCreateContext(eglDisplay(), config(), EGL_NO_CONTEXT, context_attribs);
+#else
+    const EGLint context_attribs_31_core[] = {
+        EGL_CONTEXT_MAJOR_VERSION_KHR, 3,
+        EGL_CONTEXT_MINOR_VERSION_KHR, 1,
+        EGL_CONTEXT_FLAGS_KHR,         EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR,
+        EGL_NONE
+    };
+
+    const EGLint context_attribs_legacy[] = {
+        EGL_NONE
+    };
+
+    const char* eglExtensionsCString = eglQueryString(eglDisplay(), EGL_EXTENSIONS);
+    const QList<QByteArray> extensions = QByteArray::fromRawData(eglExtensionsCString, qstrlen(eglExtensionsCString)).split(' ');
+
+    // Try to create a 3.1 core context
+    if (options->glCoreProfile() && extensions.contains(QByteArrayLiteral("EGL_KHR_create_context")))
+        context = eglCreateContext(eglDisplay(), config(), EGL_NO_CONTEXT, context_attribs_31_core);
+
+    if (context == EGL_NO_CONTEXT)
+        context = eglCreateContext(eglDisplay(), config(), EGL_NO_CONTEXT, context_attribs_legacy);
+#endif
+
+    if (context == EGL_NO_CONTEXT) {
+        qCCritical(KWIN_CORE) << "Create Context failed";
+        return false;
+    }
+    setContext(context);
+
+    EGLSurface surface = EGL_NO_SURFACE;
+    m_gbmSurface = gbm_surface_create(m_device, m_backend->size().width(), m_backend->size().height(),
+                                      GBM_FORMAT_XRGB8888, GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
+    if (!m_gbmSurface) {
+        qCCritical(KWIN_CORE) << "Create gbm surface failed";
+        return false;
+    }
+    surface = eglCreatePlatformWindowSurfaceEXT(eglDisplay(), config(), (void *) m_gbmSurface, nullptr);
+
+    if (surface == EGL_NO_SURFACE) {
+        qCCritical(KWIN_CORE) << "Create Window Surface failed";
+        return false;
+    }
+    setSurface(surface);
+
+    return makeContextCurrent();
+}
+
+bool EglGbmBackend::makeContextCurrent()
+{
+    if (eglMakeCurrent(eglDisplay(), surface(), surface(), context()) == EGL_FALSE) {
+        qCCritical(KWIN_CORE) << "Make Context Current failed";
+        return false;
+    }
+
+    EGLint error = eglGetError();
+    if (error != EGL_SUCCESS) {
+        qCWarning(KWIN_CORE) << "Error occurred while creating context " << error;
+        return false;
+    }
+    return true;
+}
+
+bool EglGbmBackend::initBufferConfigs()
+{
+    const EGLint config_attribs[] = {
+        EGL_SURFACE_TYPE,         EGL_WINDOW_BIT,
+        EGL_RED_SIZE,             1,
+        EGL_GREEN_SIZE,           1,
+        EGL_BLUE_SIZE,            1,
+        EGL_ALPHA_SIZE,           0,
+#ifdef KWIN_HAVE_OPENGLES
+        EGL_RENDERABLE_TYPE,      EGL_OPENGL_ES2_BIT,
+#else
+        EGL_RENDERABLE_TYPE,      EGL_OPENGL_BIT,
+#endif
+        EGL_CONFIG_CAVEAT,        EGL_NONE,
+        EGL_NONE,
+    };
+
+    EGLint count;
+    EGLConfig configs[1024];
+    if (eglChooseConfig(eglDisplay(), config_attribs, configs, 1, &count) == EGL_FALSE) {
+        qCCritical(KWIN_CORE) << "choose config failed";
+        return false;
+    }
+    if (count != 1) {
+        qCCritical(KWIN_CORE) << "choose config did not return a config" << count;
+        return false;
+    }
+    setConfig(configs[0]);
+
+    return true;
+}
+
+void EglGbmBackend::present()
+{
+    eglSwapBuffers(eglDisplay(), surface());
+    auto oldBuffer = m_frontBuffer;
+    m_frontBuffer = m_backend->createBuffer(m_gbmSurface);
+    m_backend->present(m_frontBuffer);
+    delete oldBuffer;
+    if (supportsBufferAge()) {
+        eglQuerySurface(eglDisplay(), surface(), EGL_BUFFER_AGE_EXT, &m_bufferAge);
+    }
+}
+
+void EglGbmBackend::screenGeometryChanged(const QSize &size)
+{
+    Q_UNUSED(size)
+    // TODO, create new buffer?
+}
+
+SceneOpenGL::TexturePrivate *EglGbmBackend::createBackendTexture(SceneOpenGL::Texture *texture)
+{
+    return new EglGbmTexture(texture, this);
+}
+
+QRegion EglGbmBackend::prepareRenderingFrame()
+{
+    QRegion repaint;
+    if (supportsBufferAge())
+        repaint = accumulatedDamageHistory(m_bufferAge);
+    startRenderTimer();
+    return repaint;
+}
+
+void EglGbmBackend::endRenderingFrame(const QRegion &renderedRegion, const QRegion &damagedRegion)
+{
+    if (damagedRegion.isEmpty()) {
+
+        // If the damaged region of a window is fully occluded, the only
+        // rendering done, if any, will have been to repair a reused back
+        // buffer, making it identical to the front buffer.
+        //
+        // In this case we won't post the back buffer. Instead we'll just
+        // set the buffer age to 1, so the repaired regions won't be
+        // rendered again in the next frame.
+        if (!renderedRegion.isEmpty())
+            glFlush();
+
+        m_bufferAge = 1;
+        return;
+    }
+    present();
+
+    // Save the damaged region to history
+    if (supportsBufferAge())
+        addToDamageHistory(damagedRegion);
+}
+
+bool EglGbmBackend::usesOverlayWindow() const
+{
+    return false;
+}
+
+/************************************************
+ * EglTexture
+ ************************************************/
+
+EglGbmTexture::EglGbmTexture(KWin::SceneOpenGL::Texture *texture, EglGbmBackend *backend)
+    : AbstractEglTexture(texture, backend)
+{
+}
+
+EglGbmTexture::~EglGbmTexture() = default;
+
+} // namespace

egl_gbm_backend.h

+/********************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (C) 2015 Martin Gräßlin <mgraesslin@kde.org>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*********************************************************************/
+#ifndef KWIN_EGL_GBM_BACKEND_H
+#define KWIN_EGL_GBM_BACKEND_H
+#include "abstract_egl_backend.h"
+#include "scene_opengl.h"
+
+struct gbm_device;
+struct gbm_surface;
+
+namespace KWin
+{
+class DrmBackend;
+class DrmBuffer;
+
+/**
+ * @brief OpenGL Backend using Egl on a GBM surface.
+ **/
+class EglGbmBackend : public QObject, public AbstractEglBackend
+{
+    Q_OBJECT
+public:
+    EglGbmBackend(DrmBackend *b);
+    virtual ~EglGbmBackend();