Common: Add DRM display helper class and GBM GL context

CMakeLists.txt

@@ -36,6 +36,9 @@ endif()
 if(LINUX OR ANDROID)
   option(USE_EGL "Support EGL OpenGL context creation" ON)
 endif()
+if(LINUX AND NOT ANDROID)
+  option(USE_DRMKMS "Support DRM/KMS display and contexts" OFF)
+endif()
 
 # Force EGL when using Wayland
 if(USE_WAYLAND)
@@ -112,6 +115,11 @@ if(USE_WAYLAND)
   find_package(Wayland REQUIRED Egl)
   message(STATUS "Wayland support enabled")
 endif()
+if(USE_DRMKMS)
+  find_package(GBM REQUIRED)
+  find_package(Libdrm REQUIRED)
+  message(STATUS "DRM/KMS support enabled")
+endif()
 
 # Set _DEBUG macro for Debug builds.
 set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D_DEBUG")

CMakeModules/FindGBM.cmake

@@ -0,0 +1,70 @@
+# https://fossies.org/linux/misc/xbmc-18.9-Leia.tar.gz/xbmc-18.9-Leia/cmake/modules/FindGBM.cmake?m=t
+
+# FindGBM
+# ----------
+# Finds the GBM library
+#
+# This will define the following variables::
+#
+# GBM_FOUND - system has GBM
+# GBM_INCLUDE_DIRS - the GBM include directory
+# GBM_LIBRARIES - the GBM libraries
+# GBM_DEFINITIONS  - the GBM definitions
+#
+# and the following imported targets::
+#
+#   GBM::GBM   - The GBM library
+
+if(PKG_CONFIG_FOUND)
+  pkg_check_modules(PC_GBM gbm QUIET)
+endif()
+
+find_path(GBM_INCLUDE_DIR NAMES gbm.h
+                          PATHS ${PC_GBM_INCLUDEDIR})
+find_library(GBM_LIBRARY NAMES gbm
+                         PATHS ${PC_GBM_LIBDIR})
+
+set(GBM_VERSION ${PC_GBM_VERSION})
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(GBM
+                                  REQUIRED_VARS GBM_LIBRARY GBM_INCLUDE_DIR
+                                  VERSION_VAR GBM_VERSION)
+
+include(CheckCSourceCompiles)
+set(CMAKE_REQUIRED_LIBRARIES ${GBM_LIBRARY})
+check_c_source_compiles("#include <gbm.h>
+
+                         int main()
+                         {
+                           gbm_bo_map(NULL, 0, 0, 0, 0, GBM_BO_TRANSFER_WRITE, NULL, NULL);
+                         }
+                         " GBM_HAS_BO_MAP)
+
+check_c_source_compiles("#include <gbm.h>
+
+                         int main()
+                         {
+                           gbm_surface_create_with_modifiers(NULL, 0, 0, 0, NULL, 0);
+                         }
+                         " GBM_HAS_MODIFIERS)
+
+if(GBM_FOUND)
+  set(GBM_LIBRARIES ${GBM_LIBRARY})
+  set(GBM_INCLUDE_DIRS ${GBM_INCLUDE_DIR})
+  set(GBM_DEFINITIONS -DHAVE_GBM=1)
+  if(GBM_HAS_BO_MAP)
+    list(APPEND GBM_DEFINITIONS -DHAS_GBM_BO_MAP=1)
+  endif()
+  if(GBM_HAS_MODIFIERS)
+    list(APPEND GBM_DEFINITIONS -DHAS_GBM_MODIFIERS=1)
+  endif()
+  if(NOT TARGET GBM::GBM)
+    add_library(GBM::GBM UNKNOWN IMPORTED)
+    set_target_properties(GBM::GBM PROPERTIES
+                                   IMPORTED_LOCATION "${GBM_LIBRARY}"
+                                   INTERFACE_INCLUDE_DIRECTORIES "${GBM_INCLUDE_DIR}")
+  endif()
+endif()
+
+mark_as_advanced(GBM_INCLUDE_DIR GBM_LIBRARY)

CMakeModules/FindLIBEVDEV.cmake

@@ -0,0 +1,33 @@
+# - Try to find libevdev
+# Once done this will define
+#  LIBEVDEV_FOUND - System has libevdev
+#  LIBEVDEV_INCLUDE_DIRS - The libevdev include directories
+#  LIBEVDEV_LIBRARIES - The libraries needed to use libevdev
+
+find_package(PkgConfig)
+pkg_check_modules(PC_LIBEVDEV QUIET libevdev)
+
+FIND_PATH(
+    LIBEVDEV_INCLUDE_DIR libevdev/libevdev.h
+    HINTS ${PC_LIBEVDEV_INCLUDEDIR} ${PC_LIBEVDEV_INCLUDE_DIRS}
+    /usr/include
+    /usr/local/include
+    ${LIBEVDEV_PATH_INCLUDES}
+)
+
+FIND_LIBRARY(
+    LIBEVDEV_LIBRARY
+    NAMES evdev libevdev
+    HINTS ${PC_LIBEVDEV_LIBDIR} ${PC_LIBEVDEV_LIBRARY_DIRS}
+    PATHS ${ADDITIONAL_LIBRARY_PATHS}
+        ${LIBEVDEV_PATH_LIB}
+)
+
+set(LIBEVDEV_LIBRARIES ${LIBEVDEV_LIBRARY} )
+set(LIBEVDEV_INCLUDE_DIRS ${LIBEVDEV_INCLUDE_DIR} )
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LIBEVDEV  DEFAULT_MSG
+                                  LIBEVDEV_LIBRARY LIBEVDEV_INCLUDE_DIR)
+
+mark_as_advanced(LIBEVDEV_INCLUDE_DIR LIBEVDEV_LIBRARY )

CMakeModules/FindLibdrm.cmake

@@ -0,0 +1,107 @@
+# https://raw.githubusercontent.com/KDE/kwin/master/cmake/modules/FindLibdrm.cmake
+
+#.rst:
+# FindLibdrm
+# -------
+#
+# Try to find libdrm on a Unix system.
+#
+# This will define the following variables:
+#
+# ``Libdrm_FOUND``
+#     True if (the requested version of) libdrm is available
+# ``Libdrm_VERSION``
+#     The version of libdrm
+# ``Libdrm_LIBRARIES``
+#     This can be passed to target_link_libraries() instead of the ``Libdrm::Libdrm``
+#     target
+# ``Libdrm_INCLUDE_DIRS``
+#     This should be passed to target_include_directories() if the target is not
+#     used for linking
+# ``Libdrm_DEFINITIONS``
+#     This should be passed to target_compile_options() if the target is not
+#     used for linking
+#
+# If ``Libdrm_FOUND`` is TRUE, it will also define the following imported target:
+#
+# ``Libdrm::Libdrm``
+#     The libdrm 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.
+
+#=============================================================================
+# SPDX-FileCopyrightText: 2014 Alex Merry <alex.merry@kde.org>
+# SPDX-FileCopyrightText: 2014 Martin Gräßlin <mgraesslin@kde.org>
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#=============================================================================
+
+if(CMAKE_VERSION VERSION_LESS 2.8.12)
+    message(FATAL_ERROR "CMake 2.8.12 is required by FindLibdrm.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 FindLibdrm.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_Libdrm QUIET libdrm)
+
+    set(Libdrm_DEFINITIONS ${PKG_Libdrm_CFLAGS_OTHER})
+    set(Libdrm_VERSION ${PKG_Libdrm_VERSION})
+
+    find_path(Libdrm_INCLUDE_DIR
+        NAMES
+            xf86drm.h
+        HINTS
+            ${PKG_Libdrm_INCLUDE_DIRS}
+    )
+    find_library(Libdrm_LIBRARY
+        NAMES
+            drm
+        HINTS
+            ${PKG_Libdrm_LIBRARY_DIRS}
+    )
+
+    include(FindPackageHandleStandardArgs)
+    find_package_handle_standard_args(Libdrm
+        FOUND_VAR
+            Libdrm_FOUND
+        REQUIRED_VARS
+            Libdrm_LIBRARY
+            Libdrm_INCLUDE_DIR
+        VERSION_VAR
+            Libdrm_VERSION
+    )
+
+    if(Libdrm_FOUND AND NOT TARGET Libdrm::Libdrm)
+        add_library(Libdrm::Libdrm UNKNOWN IMPORTED)
+        set_target_properties(Libdrm::Libdrm PROPERTIES
+            IMPORTED_LOCATION "${Libdrm_LIBRARY}"
+            INTERFACE_COMPILE_OPTIONS "${Libdrm_DEFINITIONS}"
+            INTERFACE_INCLUDE_DIRECTORIES "${Libdrm_INCLUDE_DIR}"
+            INTERFACE_INCLUDE_DIRECTORIES "${Libdrm_INCLUDE_DIR}/libdrm"
+        )
+    endif()
+
+    mark_as_advanced(Libdrm_LIBRARY Libdrm_INCLUDE_DIR)
+
+    # compatibility variables
+    set(Libdrm_LIBRARIES ${Libdrm_LIBRARY})
+    set(Libdrm_INCLUDE_DIRS ${Libdrm_INCLUDE_DIR} "${Libdrm_INCLUDE_DIR}/libdrm")
+    set(Libdrm_VERSION_STRING ${Libdrm_VERSION})
+
+else()
+    message(STATUS "FindLibdrm.cmake cannot find libdrm on Windows systems.")
+    set(Libdrm_FOUND FALSE)
+endif()
+
+include(FeatureSummary)
+set_package_properties(Libdrm PROPERTIES
+    URL "https://wiki.freedesktop.org/dri/"
+    DESCRIPTION "Userspace interface to kernel DRM services."
+)

src/common/CMakeLists.txt

@@ -142,6 +142,14 @@ if(USE_X11)
   target_link_libraries(common PRIVATE "${X11_LIBRARIES}")
 endif()
 
+if(USE_DRMKMS)
+  target_sources(common PRIVATE
+    drm_display.cpp
+    drm_display.h
+  )
+  target_link_libraries(common PUBLIC Libdrm::Libdrm)
+endif()
+
 if(USE_EGL)
   target_sources(common PRIVATE
     gl/context_egl.cpp
@@ -161,6 +169,14 @@ if(USE_EGL)
       gl/context_egl_android.h
     )
   endif()
+  if(USE_DRMKMS)
+    target_compile_definitions(common PRIVATE "-DUSE_GBM=1")
+    target_sources(common PRIVATE
+      gl/context_egl_gbm.cpp
+      gl/context_egl_gbm.h
+    )
+    target_link_libraries(common PUBLIC GBM::GBM)
+  endif()
 endif()
 
 if(USE_X11)

src/common/drm_display.cpp

@@ -0,0 +1,249 @@
+#include "drm_display.h"
+#include "common/assert.h"
+#include "common/log.h"
+#include "common/string.h"
+#include "file_system.h"
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+Log_SetChannel(DRMDisplay);
+
+DRMDisplay::DRMDisplay(int card /*= 1*/) : m_card_id(card) {}
+
+DRMDisplay::~DRMDisplay()
+{
+  if (m_connector)
+    drmModeFreeConnector(m_connector);
+
+  if (m_card_fd >= 0)
+    close(m_card_fd);
+}
+
+// https://gist.github.com/Miouyouyou/89e9fe56a2c59bce7d4a18a858f389ef
+
+static uint32_t find_crtc_for_encoder(const drmModeRes* resources, const drmModeEncoder* encoder)
+{
+  int i;
+
+  for (i = 0; i < resources->count_crtcs; i++)
+  {
+    /* possible_crtcs is a bitmask as described here:
+     * https://dvdhrm.wordpress.com/2012/09/13/linux-drm-mode-setting-api
+     */
+    const uint32_t crtc_mask = 1 << i;
+    const uint32_t crtc_id = resources->crtcs[i];
+    if (encoder->possible_crtcs & crtc_mask)
+    {
+      return crtc_id;
+    }
+  }
+
+  /* no match found */
+  return -1;
+}
+
+static uint32_t find_crtc_for_connector(int card_fd, const drmModeRes* resources, const drmModeConnector* connector)
+{
+  int i;
+
+  for (i = 0; i < connector->count_encoders; i++)
+  {
+    const uint32_t encoder_id = connector->encoders[i];
+    drmModeEncoder* encoder = drmModeGetEncoder(card_fd, encoder_id);
+
+    if (encoder)
+    {
+      const uint32_t crtc_id = find_crtc_for_encoder(resources, encoder);
+
+      drmModeFreeEncoder(encoder);
+      if (crtc_id != 0)
+      {
+        return crtc_id;
+      }
+    }
+  }
+
+  /* no match found */
+  return -1;
+}
+
+bool DRMDisplay::Initialize()
+{
+  if (m_card_id < 0)
+  {
+    for (int i = 0; i < 10; i++)
+    {
+      if (TryOpeningCard(i))
+        return true;
+    }
+
+    return false;
+  }
+
+  return TryOpeningCard(m_card_id);
+}
+
+bool DRMDisplay::TryOpeningCard(int card)
+{
+  if (m_card_fd >= 0)
+    close(m_card_fd);
+
+  m_card_fd = open(TinyString::FromFormat("/dev/dri/card%d", card), O_RDWR);
+  if (m_card_fd < 0)
+  {
+    Log_ErrorPrintf("open(/dev/dri/card%d) failed: %d (%s)", card, errno, strerror(errno));
+    return false;
+  }
+
+  drmModeRes* resources = drmModeGetResources(m_card_fd);
+  if (!resources)
+  {
+    Log_ErrorPrintf("drmModeGetResources() failed: %d (%s)", errno, strerror(errno));
+    return false;
+  }
+
+  Assert(!m_connector);
+
+  for (int i = 0; i < resources->count_connectors; i++)
+  {
+    drmModeConnector* next_connector = drmModeGetConnector(m_card_fd, resources->connectors[i]);
+    if (next_connector->connection == DRM_MODE_CONNECTED)
+    {
+      m_connector = next_connector;
+      break;
+    }
+
+    drmModeFreeConnector(next_connector);
+  }
+
+  if (!m_connector)
+  {
+    Log_ErrorPrintf("No connector found");
+    drmModeFreeResources(resources);
+    return false;
+  }
+
+  for (int i = 0; i < m_connector->count_modes; i++)
+  {
+    drmModeModeInfo* next_mode = &m_connector->modes[i];
+    if (next_mode->type & DRM_MODE_TYPE_PREFERRED)
+    {
+      m_mode = next_mode;
+      break;
+    }
+
+    if (!m_mode || (next_mode->hdisplay * next_mode->vdisplay) > (m_mode->hdisplay * m_mode->vdisplay))
+    {
+      m_mode = next_mode;
+    }
+  }
+
+  if (!m_mode)
+  {
+    Log_ErrorPrintf("No mode found");
+    drmModeFreeResources(resources);
+    return false;
+  }
+
+  drmModeEncoder* encoder = nullptr;
+  for (int i = 0; i < resources->count_encoders; i++)
+  {
+    drmModeEncoder* next_encoder = drmModeGetEncoder(m_card_fd, resources->encoders[i]);
+    if (next_encoder->encoder_id == m_connector->encoder_id)
+    {
+      encoder = next_encoder;
+      m_crtc_id = encoder->crtc_id;
+      break;
+    }
+
+    drmModeFreeEncoder(next_encoder);
+  }
+
+  if (encoder)
+  {
+    drmModeFreeEncoder(encoder);
+  }
+  else
+  {
+    m_crtc_id = find_crtc_for_connector(m_card_fd, resources, m_connector);
+    if (m_crtc_id == 0)
+    {
+      Log_ErrorPrintf("No CRTC found");
+      drmModeFreeResources(resources);
+      return false;
+    }
+  }
+
+  drmModeFreeResources(resources);
+
+  m_card_id = card;
+  return true;
+}
+
+std::optional<u32> DRMDisplay::AddBuffer(u32 width, u32 height, u32 format, u32 handle, u32 pitch, u32 offset)
+{
+  uint32_t bo_handles[4] = {handle, 0, 0, 0};
+  uint32_t pitches[4] = {pitch, 0, 0, 0};
+  uint32_t offsets[4] = {offset, 0, 0, 0};
+
+  u32 fb_id;
+  int res = drmModeAddFB2(m_card_fd, width, height, format, bo_handles, pitches, offsets, &fb_id, 0);
+  if (res != 0)
+  {
+    Log_ErrorPrintf("drmModeAddFB2() failed: %d", res);
+    return std::nullopt;
+  }
+
+  return fb_id;
+}
+
+void DRMDisplay::RemoveBuffer(u32 fb_id)
+{
+  drmModeRmFB(m_card_fd, fb_id);
+}
+
+void DRMDisplay::PresentBuffer(u32 fb_id, bool wait_for_vsync)
+{
+  if (!wait_for_vsync)
+  {
+    u32 connector_id = m_connector->connector_id;
+    int res = drmModeSetCrtc(m_card_fd, m_crtc_id, fb_id, 0, 0, &connector_id, 1, m_mode);
+    if (res != 0)
+      Log_ErrorPrintf("drmModeSetCrtc() failed: %d", res);
+
+    return;
+  }
+
+  bool waiting_for_flip = true;
+  drmEventContext event_ctx = {};
+  event_ctx.version = DRM_EVENT_CONTEXT_VERSION;
+  event_ctx.page_flip_handler = [](int fd, unsigned int frame, unsigned int sec, unsigned int usec, void* data) {
+    *reinterpret_cast<bool*>(data) = false;
+  };
+
+  int res = drmModePageFlip(m_card_fd, m_crtc_id, fb_id, DRM_MODE_PAGE_FLIP_EVENT, &waiting_for_flip);
+  if (res != 0)
+  {
+    Log_ErrorPrintf("drmModePageFlip() failed: %d", res);
+    return;
+  }
+
+  while (waiting_for_flip)
+  {
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(m_card_fd, &fds);
+    int res = select(m_card_fd + 1, &fds, nullptr, nullptr, nullptr);
+    if (res < 0)
+    {
+      Log_ErrorPrintf("select() failed: %d", errno);
+      break;
+    }
+    else if (res == 0)
+    {
+      continue;
+    }
+
+    drmHandleEvent(m_card_fd, &event_ctx);
+  }
+}

src/common/drm_display.h

@@ -0,0 +1,38 @@
+#pragma once
+#include "core/types.h"
+#include <array>
+#include <optional>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+
+class DRMDisplay
+{
+public:
+  DRMDisplay(int card = -1);
+  ~DRMDisplay();
+
+  bool Initialize();
+
+  int GetCardID() const { return m_card_id; }
+  int GetCardFD() const { return m_card_fd; }
+  u32 GetWidth() const { return m_mode->hdisplay; }
+  u32 GetHeight() const { return m_mode->vdisplay; }
+
+  std::optional<u32> AddBuffer(u32 width, u32 height, u32 format, u32 handle, u32 pitch, u32 offset);
+  void RemoveBuffer(u32 fb_id);
+  void PresentBuffer(u32 fb_id, bool wait_for_vsync);
+
+private:
+  enum : u32
+  {
+    MAX_BUFFERS = 5
+  };
+
+  bool TryOpeningCard(int card);
+
+  int m_card_id = 0;
+  int m_card_fd = -1;
+  u32 m_crtc_id = 0;
+  drmModeConnector* m_connector = nullptr;
+  drmModeModeInfo* m_mode = nullptr;
+};

src/common/gl/context.cpp

@@ -11,18 +11,21 @@ Log_SetChannel(GL::Context);
 
 #if defined(WIN32) && !defined(_M_ARM64)
 #include "context_wgl.h"
-#elif defined(__APPLE__)
+#elif defined(__APPLE__) && !defined(LIBERTRO)
 #include "context_agl.h"
 #endif
 
 #ifdef USE_EGL
-#if defined(USE_X11) || defined(USE_WAYLAND)
+#if defined(USE_X11) || defined(USE_WAYLAND) || defined(USE_GBM)
 #if defined(USE_X11)
 #include "context_egl_x11.h"
 #endif
 #if defined(USE_WAYLAND)
 #include "context_egl_wayland.h"
 #endif
+#if defined(USE_GBM)
+#include "context_egl_gbm.h"
+#endif
 #elif defined(ANDROID)
 #include "context_egl_android.h"
 #else
@@ -77,7 +80,7 @@ std::unique_ptr<GL::Context> Context::Create(const WindowInfo& wi, const Version
   std::unique_ptr<Context> context;
 #if defined(WIN32) && !defined(_M_ARM64)
   context = ContextWGL::Create(wi, versions_to_try, num_versions_to_try);
-#elif defined(__APPLE__)
+#elif defined(__APPLE__) && !defined(LIBRETRO)
   context = ContextAGL::Create(wi, versions_to_try, num_versions_to_try);
 #elif defined(ANDROID)
 #ifdef USE_EGL
@@ -105,6 +108,11 @@ std::unique_ptr<GL::Context> Context::Create(const WindowInfo& wi, const Version
     context = ContextEGLWayland::Create(wi, versions_to_try, num_versions_to_try);
 #endif
 
+#if defined(USE_GBM)
+  if (wi.type == WindowInfo::Type::DRM)
+    context = ContextEGLGBM::Create(wi, versions_to_try, num_versions_to_try);
+#endif
+
   if (!context)
     return nullptr;
 

src/common/gl/context_egl.cpp

@@ -1,6 +1,8 @@
 #include "context_egl.h"
 #include "../assert.h"
 #include "../log.h"
+#include <optional>
+#include <vector>
 Log_SetChannel(GL::ContextEGL);
 
 namespace GL {
@@ -33,12 +35,8 @@ bool ContextEGL::Initialize(const Version* versions_to_try, size_t num_versions_
     return false;
   }
 
-  m_display = eglGetDisplay(static_cast<EGLNativeDisplayType>(m_wi.display_connection));
-  if (!m_display)
-  {
-    Log_ErrorPrintf("eglGetDisplay() failed: %d", eglGetError());
+  if (!SetDisplay())
     return false;
-  }
 
   int egl_major, egl_minor;
   if (!eglInitialize(m_display, &egl_major, &egl_minor))
@@ -66,6 +64,18 @@ bool ContextEGL::Initialize(const Version* versions_to_try, size_t num_versions_
   return false;
 }
 
+bool ContextEGL::SetDisplay()
+{
+  m_display = eglGetDisplay(static_cast<EGLNativeDisplayType>(m_wi.display_connection));
+  if (!m_display)
+  {
+    Log_ErrorPrintf("eglGetDisplay() failed: %d", eglGetError());
+    return false;
+  }
+
+  return true;
+}
+
 void* ContextEGL::GetProcAddress(const char* name)
 {
   return reinterpret_cast<void*>(eglGetProcAddress(name));
@@ -216,6 +226,36 @@ bool ContextEGL::CreatePBufferSurface()
   return true;
 }
 
+bool ContextEGL::CheckConfigSurfaceFormat(EGLConfig config, WindowInfo::SurfaceFormat format) const
+{
+  int red_size, green_size, blue_size, alpha_size;
+  if (!eglGetConfigAttrib(m_display, config, EGL_RED_SIZE, &red_size) ||
+      !eglGetConfigAttrib(m_display, config, EGL_GREEN_SIZE, &green_size) ||
+      !eglGetConfigAttrib(m_display, config, EGL_BLUE_SIZE, &blue_size) ||
+      !eglGetConfigAttrib(m_display, config, EGL_ALPHA_SIZE, &alpha_size))
+  {
+    return false;
+  }
+
+  switch (format)
+  {
+    case WindowInfo::SurfaceFormat::Auto:
+      return true;
+
+    case WindowInfo::SurfaceFormat::RGB8:
+      return (red_size == 8 && green_size == 8 && blue_size == 8);
+
+    case WindowInfo::SurfaceFormat::RGBA8:
+      return (red_size == 8 && green_size == 8 && blue_size == 8 && alpha_size == 8);
+
+    case WindowInfo::SurfaceFormat::RGB565:
+      return (red_size == 5 && green_size == 6 && blue_size == 5);
+
+    default:
+      return false;
+  }
+}
+
 bool ContextEGL::CreateContext(const Version& version, EGLContext share_context)
 {
   Log_DevPrintf(
@@ -263,6 +303,9 @@ bool ContextEGL::CreateContext(const Version& version, EGLContext share_context)
       surface_attribs[nsurface_attribs++] = 5;
       break;
 
+    case WindowInfo::SurfaceFormat::Auto:
+      break;
+
     default:
       UnreachableCode();
       break;
@@ -272,13 +315,36 @@ bool ContextEGL::CreateContext(const Version& version, EGLContext share_context)
   surface_attribs[nsurface_attribs++] = 0;
 
   EGLint num_configs;
-  EGLConfig config;
-  if (!eglChooseConfig(m_display, surface_attribs, &config, 1, &num_configs) || num_configs == 0)
+  if (!eglChooseConfig(m_display, surface_attribs, nullptr, 0, &num_configs) || num_configs == 0)
   {
     Log_ErrorPrintf("eglChooseConfig() failed: %d", eglGetError());
     return false;
   }
 
+  std::vector<EGLConfig> configs(static_cast<u32>(num_configs));
+  if (!eglChooseConfig(m_display, surface_attribs, configs.data(), num_configs, &num_configs))
+  {
+    Log_ErrorPrintf("eglChooseConfig() failed: %d", eglGetError());
+    return false;
+  }
+  configs.resize(static_cast<u32>(num_configs));
+
+  std::optional<EGLConfig> config;
+  for (EGLConfig check_config : configs)
+  {
+    if (CheckConfigSurfaceFormat(check_config, m_wi.surface_format))
+    {
+      config = check_config;
+      break;
+    }
+  }
+
+  if (!config.has_value())
+  {
+    Log_WarningPrintf("No EGL configs matched exactly, using first.");
+    config = configs.front();
+  }
+
   int attribs[8];
   int nattribs = 0;
   if (version.profile != Profile::NoProfile)
@@ -297,7 +363,7 @@ bool ContextEGL::CreateContext(const Version& version, EGLContext share_context)
     return false;
   }
 
-  m_context = eglCreateContext(m_display, config, share_context, attribs);
+  m_context = eglCreateContext(m_display, config.value(), share_context, attribs);
   if (!m_context)
   {
     Log_ErrorPrintf("eglCreateContext() failed: %d", eglGetError());
@@ -308,7 +374,7 @@ bool ContextEGL::CreateContext(const Version& version, EGLContext share_context)
     "Got version %u.%u (%s)", version.major_version, version.minor_version,
     version.profile == Context::Profile::ES ? "ES" : (version.profile == Context::Profile::Core ? "Core" : "None"));
 
-  m_config = config;
+  m_config = config.value();
   m_version = version;
   return true;
 }

src/common/gl/context_egl.h

@@ -23,6 +23,7 @@ public:
   virtual std::unique_ptr<Context> CreateSharedContext(const WindowInfo& wi) override;
 
 protected:
+  virtual bool SetDisplay();
   virtual EGLNativeWindowType GetNativeWindow(EGLConfig config);
 
   bool Initialize(const Version* versions_to_try, size_t num_versions_to_try);
@@ -31,6 +32,7 @@ protected:
   bool CreateContextAndSurface(const Version& version, EGLContext share_context, bool make_current);
   bool CreateSurface();
   bool CreatePBufferSurface();
+  bool CheckConfigSurfaceFormat(EGLConfig config, WindowInfo::SurfaceFormat format) const;
 
   EGLDisplay m_display = EGL_NO_DISPLAY;
   EGLSurface m_surface = EGL_NO_SURFACE;

src/common/gl/context_egl_gbm.cpp

@@ -0,0 +1,253 @@
+#include "context_egl_gbm.h"
+#include "../assert.h"
+#include "../log.h"
+#include <drm.h>
+#include <drm_fourcc.h>
+#include <gbm.h>
+Log_SetChannel(GL::ContextEGLGBM);
+
+namespace GL {
+ContextEGLGBM::ContextEGLGBM(const WindowInfo& wi) : ContextEGL(wi)
+{
+#ifdef CONTEXT_EGL_GBM_USE_PRESENT_THREAD
+  StartPresentThread();
+#endif
+}
+
+ContextEGLGBM::~ContextEGLGBM()
+{
+#ifdef CONTEXT_EGL_GBM_USE_PRESENT_THREAD
+  StopPresentThread();
+  Assert(!m_current_present_buffer);
+#endif
+
+  while (m_num_buffers > 0)
+  {
+    Buffer& buffer = m_buffers[--m_num_buffers];
+    GetDisplay()->RemoveBuffer(buffer.fb_id);
+  }
+
+  if (m_fb_surface)
+    gbm_surface_destroy(m_fb_surface);
+
+  if (m_gbm_device)
+    gbm_device_destroy(m_gbm_device);
+}
+
+std::unique_ptr<Context> ContextEGLGBM::Create(const WindowInfo& wi, const Version* versions_to_try,
+                                               size_t num_versions_to_try)
+{
+  std::unique_ptr<ContextEGLGBM> context = std::make_unique<ContextEGLGBM>(wi);
+  if (!context->CreateGBMDevice() || !context->Initialize(versions_to_try, num_versions_to_try))
+    return nullptr;
+
+  return context;
+}
+
+std::unique_ptr<Context> ContextEGLGBM::CreateSharedContext(const WindowInfo& wi)
+{
+  std::unique_ptr<ContextEGLGBM> context = std::make_unique<ContextEGLGBM>(wi);
+  context->m_display = m_display;
+
+  if (!context->CreateContextAndSurface(m_version, m_context, false))
+    return nullptr;
+
+  return context;
+}
+
+void ContextEGLGBM::ResizeSurface(u32 new_surface_width, u32 new_surface_height)
+{
+  ContextEGL::ResizeSurface(new_surface_width, new_surface_height);
+}
+
+bool ContextEGLGBM::CreateGBMDevice()
+{
+  Assert(!m_gbm_device);
+  m_gbm_device = gbm_create_device(GetDisplay()->GetCardFD());
+  if (!m_gbm_device)
+  {
+    Log_ErrorPrintf("gbm_create_device() failed: %d", errno);
+    return false;
+  }
+
+  return true;
+}
+
+bool ContextEGLGBM::SetDisplay()
+{
+  if (!eglGetPlatformDisplayEXT)
+  {
+    Log_ErrorPrintf("eglGetPlatformDisplayEXT() not loaded");
+    return false;
+  }
+
+  m_display = eglGetPlatformDisplayEXT(EGL_PLATFORM_GBM_KHR, m_gbm_device, nullptr);
+  if (!m_display)
+  {
+    Log_ErrorPrintf("eglGetPlatformDisplayEXT() failed");
+    return false;
+  }
+
+  return true;
+}
+
+EGLNativeWindowType ContextEGLGBM::GetNativeWindow(EGLConfig config)
+{
+  EGLint visual_id;
+  eglGetConfigAttrib(m_display, config, EGL_NATIVE_VISUAL_ID, &visual_id);
+
+  Assert(!m_fb_surface);
+  m_fb_surface = gbm_surface_create(m_gbm_device, GetDisplay()->GetWidth(), GetDisplay()->GetHeight(),
+                                    static_cast<u32>(visual_id), GBM_BO_USE_RENDERING | GBM_BO_USE_SCANOUT);
+  if (!m_fb_surface)
+  {
+    Log_ErrorPrintf("gbm_surface_create() failed: %d", errno);
+    return {};
+  }
+
+  return (EGLNativeWindowType)((void*)m_fb_surface);
+}
+
+ContextEGLGBM::Buffer* ContextEGLGBM::LockFrontBuffer()
+{
+  struct gbm_bo* bo = gbm_surface_lock_front_buffer(m_fb_surface);
+
+  Buffer* buffer = nullptr;
+  for (u32 i = 0; i < m_num_buffers; i++)
+  {
+    if (m_buffers[i].bo == bo)
+    {
+      buffer = &m_buffers[i];
+      break;
+    }
+  }
+
+  if (!buffer)
+  {
+    // haven't tracked this buffer yet
+    Assert(m_num_buffers < MAX_BUFFERS);
+
+    const u32 width = gbm_bo_get_width(bo);
+    const u32 height = gbm_bo_get_height(bo);
+    const u32 stride = gbm_bo_get_stride(bo);
+    const u32 format = gbm_bo_get_format(bo);
+    const u32 handle = gbm_bo_get_handle(bo).u32;
+
+    std::optional<u32> fb_id = GetDisplay()->AddBuffer(width, height, format, handle, stride, 0);
+    if (!fb_id.has_value())
+      return nullptr;
+
+    buffer = &m_buffers[m_num_buffers];
+    buffer->bo = bo;
+    buffer->fb_id = fb_id.value();
+    m_num_buffers++;
+  }
+
+  return buffer;
+}
+
+void ContextEGLGBM::ReleaseBuffer(Buffer* buffer)
+{
+  gbm_surface_release_buffer(m_fb_surface, buffer->bo);
+}
+
+void ContextEGLGBM::PresentBuffer(Buffer* buffer, bool wait_for_vsync)
+{
+  GetDisplay()->PresentBuffer(buffer->fb_id, wait_for_vsync);
+}
+
+bool ContextEGLGBM::SwapBuffers()
+{
+  if (!ContextEGL::SwapBuffers())
+    return false;
+
+#ifdef CONTEXT_EGL_GBM_USE_PRESENT_THREAD
+  std::unique_lock lock(m_present_mutex);
+  m_present_pending.store(true);
+  m_present_cv.notify_one();
+  if (m_vsync)
+    m_present_done_cv.wait(lock, [this]() { return !m_present_pending.load(); });
+#else
+  Buffer* front_buffer = LockFrontBuffer();
+  if (!front_buffer)
+    return false;
+
+  PresentSurface(front_buffer, m_vsync && m_last_front_buffer);
+
+  if (m_last_front_buffer)
+    ReleaseBuffer(m_last_front_buffer);
+
+  m_last_front_buffer = front_buffer;
+#endif
+
+  return true;
+}
+
+bool ContextEGLGBM::SetSwapInterval(s32 interval)
+{
+  if (interval < 0 || interval > 1)
+    return false;
+
+  std::unique_lock lock(m_present_mutex);
+  m_vsync = (interval > 0);
+  return true;
+}
+
+#ifdef CONTEXT_EGL_GBM_USE_PRESENT_THREAD
+
+void ContextEGLGBM::StartPresentThread()
+{
+  m_present_thread_shutdown.store(false);
+  m_present_thread = std::thread(&ContextEGLGBM::PresentThread, this);
+}
+
+void ContextEGLGBM::StopPresentThread()
+{
+  if (!m_present_thread.joinable())
+    return;
+
+  {
+    std::unique_lock lock(m_present_mutex);
+    m_present_thread_shutdown.store(true);
+    m_present_cv.notify_one();
+  }
+
+  m_present_thread.join();
+}
+
+void ContextEGLGBM::PresentThread()
+{
+  std::unique_lock lock(m_present_mutex);
+
+  while (!m_present_thread_shutdown.load())
+  {
+    m_present_cv.wait(lock);
+
+    if (!m_present_pending.load())
+      continue;
+
+    Buffer* next_buffer = LockFrontBuffer();
+    const bool wait_for_vsync = m_vsync && m_current_present_buffer;
+
+    lock.unlock();
+    PresentBuffer(next_buffer, wait_for_vsync);
+    lock.lock();
+
+    if (m_current_present_buffer)
+      ReleaseBuffer(m_current_present_buffer);
+
+    m_current_present_buffer = next_buffer;
+    m_present_pending.store(false);
+    m_present_done_cv.notify_one();
+  }
+
+  if (m_current_present_buffer)
+  {
+    ReleaseBuffer(m_current_present_buffer);
+    m_current_present_buffer = nullptr;
+  }
+}
+
+#endif
+
+} // namespace GL

src/common/gl/context_egl_gbm.h

@@ -0,0 +1,76 @@
+#pragma once
+#include "../drm_display.h"
+#include "context_egl.h"
+#include <atomic>
+#include <condition_variable>
+#include <gbm.h>
+#include <mutex>
+#include <thread>
+
+#define CONTEXT_EGL_GBM_USE_PRESENT_THREAD 1
+
+namespace GL {
+
+class ContextEGLGBM final : public ContextEGL
+{
+public:
+  ContextEGLGBM(const WindowInfo& wi);
+  ~ContextEGLGBM() override;
+
+  static std::unique_ptr<Context> Create(const WindowInfo& wi, const Version* versions_to_try,
+                                         size_t num_versions_to_try);
+
+  std::unique_ptr<Context> CreateSharedContext(const WindowInfo& wi) override;
+  void ResizeSurface(u32 new_surface_width = 0, u32 new_surface_height = 0) override;
+
+  bool SwapBuffers() override;
+  bool SetSwapInterval(s32 interval) override;
+
+protected:
+  bool SetDisplay() override;
+  EGLNativeWindowType GetNativeWindow(EGLConfig config) override;
+
+private:
+  enum : u32
+  {
+    MAX_BUFFERS = 5
+  };
+
+  struct Buffer
+  {
+    struct gbm_bo* bo;
+    u32 fb_id;
+  };
+
+  DRMDisplay* GetDisplay() { return static_cast<DRMDisplay*>(m_wi.display_connection); }
+
+  bool CreateGBMDevice();
+  Buffer* LockFrontBuffer();
+  void ReleaseBuffer(Buffer* buffer);
+  void PresentBuffer(Buffer* buffer, bool wait_for_vsync);
+
+  void StartPresentThread();
+  void StopPresentThread();
+  void PresentThread();
+
+  bool m_vsync = true;
+
+  struct gbm_device* m_gbm_device = nullptr;
+  struct gbm_surface* m_fb_surface = nullptr;
+
+#ifdef CONTEXT_EGL_GBM_USE_PRESENT_THREAD
+  std::thread m_present_thread;
+  std::mutex m_present_mutex;
+  std::condition_variable m_present_cv;
+  std::atomic_bool m_present_pending{false};
+  std::atomic_bool m_present_thread_shutdown{false};
+  std::condition_variable m_present_done_cv;
+
+  Buffer* m_current_present_buffer = nullptr;
+#endif
+
+  u32 m_num_buffers = 0;
+  std::array<Buffer, MAX_BUFFERS> m_buffers{};
+};
+
+} // namespace GL

src/common/gl/context_glx.cpp

@@ -221,6 +221,9 @@ bool ContextGLX::CreateWindow(int screen)
       attribs[nattribs++] = 5;
       break;
 
+    case WindowInfo::SurfaceFormat::Auto:
+      break;
+
     default:
       UnreachableCode();
       break;

src/common/gl/context_wgl.cpp

@@ -204,6 +204,9 @@ bool ContextWGL::InitializeDC()
       pfd.cBlueBits = 5;
       break;
 
+    case WindowInfo::SurfaceFormat::Auto:
+      break;
+
     default:
       UnreachableCode();
       break;

src/common/window_info.h

@@ -12,11 +12,13 @@ struct WindowInfo
     Wayland,
     MacOS,
     Android,
+    DRM,
   };
 
   enum class SurfaceFormat
   {
     None,
+    Auto,
     RGB8,
     RGBA8,
     RGB565,