Make ozone backend work if it can't display.

src/libANGLE/renderer/gl/egl/ozone/DisplayOzone.cpp

@@ -10,7 +10,6 @@
 
 #include <fcntl.h>
 #include <poll.h>
-#include <iostream>
 #include <unistd.h>
 #include <sys/time.h>
 
@@ -295,7 +294,7 @@ uint32_t DisplayOzone::Buffer::getDRMFB()
         uint32_t offsets[4] = {0};
         if (drmModeAddFB2(fd, mWidth, mHeight, mDRMFormatFB, handles, pitches, offsets, &mDRMFB, 0))
         {
-            std::cerr << "drmModeAddFB2 failed" << std::endl;
+            WARN() << "drmModeAddFB2 failed: " << errno << " " << strerror(errno);
         }
         else
         {
@@ -336,8 +335,8 @@ DisplayOzone::DisplayOzone(const egl::DisplayState &state)
       mMode(nullptr),
       mCRTC(nullptr),
       mSetCRTC(true),
-      mWidth(0),
-      mHeight(0),
+      mWidth(1280),
+      mHeight(1024),
       mScanning(nullptr),
       mPending(nullptr),
       mDrawing(nullptr),
@@ -358,47 +357,21 @@ DisplayOzone::~DisplayOzone()
 {
 }
 
-egl::Error DisplayOzone::initialize(egl::Display *display)
+bool DisplayOzone::hasUsableScreen(int fd)
 {
-    int fd;
-    char deviceName[30];
-    drmModeResPtr resources = nullptr;
-
-    for (int i = 0; i < 9; ++i)
-    {
-        snprintf(deviceName, sizeof(deviceName), "/dev/dri/card%d", i);
-        fd = open(deviceName, O_RDWR | O_CLOEXEC);
-        if (fd >= 0)
-        {
-            resources = drmModeGetResources(fd);
-            if (resources)
-            {
-                if (resources->count_connectors > 0)
-                {
-                    break;
-                }
-                drmModeFreeResources(resources);
-                resources = nullptr;
-            }
-            close(fd);
-        }
-    }
+    drmModeResPtr resources = drmModeGetResources(fd);
     if (!resources)
     {
-        return egl::Error(EGL_NOT_INITIALIZED, "Could not open drm device.");
+        return false;
     }
-
-    mGBM = gbm_create_device(fd);
-    if (!mGBM)
+    if (resources->count_connectors < 1)
     {
-        close(fd);
         drmModeFreeResources(resources);
-        return egl::Error(EGL_NOT_INITIALIZED, "Could not create gbm device.");
+        return false;
     }
 
     mConnector = nullptr;
-    bool monitorConnected = false;
-    for (int i = 0; !mCRTC && i < resources->count_connectors; ++i)
+    for (int i = 0; i < resources->count_connectors; ++i)
     {
         drmModeFreeConnector(mConnector);
         mConnector = drmModeGetConnector(fd, resources->connectors[i]);
@@ -406,7 +379,6 @@ egl::Error DisplayOzone::initialize(egl::Display *display)
         {
             continue;
         }
-        monitorConnected = true;
         mMode = ChooseMode(mConnector);
         if (!mMode)
         {
@@ -418,25 +390,68 @@ egl::Error DisplayOzone::initialize(egl::Display *display)
             continue;
         }
         mCRTC = drmModeGetCrtc(fd, resources->crtcs[n]);
-    }
-    drmModeFreeResources(resources);
-
         if (mCRTC)
         {
+            // found a screen
+            mGBM = gbm_create_device(fd);
+            if (mGBM)
+            {
                 mWidth  = mMode->hdisplay;
                 mHeight = mMode->vdisplay;
+                drmModeFreeResources(resources);
+                return true;
+            }
+            // can't use this screen
+            drmModeFreeCrtc(mCRTC);
+            mCRTC = nullptr;
+        }
+    }
+
+    drmModeFreeResources(resources);
+    return false;
+}
+
+egl::Error DisplayOzone::initialize(egl::Display *display)
+{
+    int fd;
+    char deviceName[30];
+
+    for (int i = 0; i < 64; ++i)
+    {
+        snprintf(deviceName, sizeof(deviceName), "/dev/dri/card%d", i);
+        fd = open(deviceName, O_RDWR | O_CLOEXEC);
+        if (fd >= 0)
+        {
+            if (hasUsableScreen(fd))
+            {
+                break;
+            }
+            close(fd);
+        }
     }
-    else if (!monitorConnected)
+
+    if (!mGBM)
+    {
+        // there's no usable screen so try to proceed without one
+        for (int i = 128; i < 192; ++i)
         {
-        // Even though there is no monitor to show it, we still do
-        // everything the same as if there were one, so we need an
-        // arbitrary size for our buffers.
-        mWidth  = 1280;
-        mHeight = 1024;
+            snprintf(deviceName, sizeof(deviceName), "/dev/dri/renderD%d", i);
+            fd = open(deviceName, O_RDWR | O_CLOEXEC);
+            if (fd >= 0)
+            {
+                mGBM = gbm_create_device(fd);
+                if (mGBM)
+                {
+                    break;
                 }
-    else
+                close(fd);
+            }
+        }
+    }
+
+    if (!mGBM)
     {
-        return egl::Error(EGL_NOT_INITIALIZED, "Failed to choose mode/crtc.");
+        return egl::Error(EGL_NOT_INITIALIZED, "Could not open drm device.");
     }
 
     // ANGLE builds its executables with an RPATH so they pull in ANGLE's libGL and libEGL.
@@ -536,7 +551,7 @@ void DisplayOzone::presentScreen()
         pfd.events = POLLIN;
         if (poll(&pfd, 1, 0) < 0)
         {
-            std::cerr << "poll failed: " << errno << " " << strerror(errno) << std::endl;
+            WARN() << "poll failed: " << errno << " " << strerror(errno);
         }
         if (pfd.revents & POLLIN)
         {
@@ -556,14 +571,14 @@ void DisplayOzone::presentScreen()
             if (drmModeSetCrtc(fd, mCRTC->crtc_id, mDrawing->getDRMFB(), 0, 0,
                                &mConnector->connector_id, 1, mMode))
             {
-                std::cerr << "set crtc failed: " << errno << " " << strerror(errno) << std::endl;
+                WARN() << "set crtc failed: " << errno << " " << strerror(errno);
             }
             mSetCRTC = false;
         }
         if (drmModePageFlip(fd, mCRTC->crtc_id, mDrawing->getDRMFB(), DRM_MODE_PAGE_FLIP_EVENT,
                             this))
         {
-            std::cerr << "page flip failed: " << errno << " " << strerror(errno) << std::endl;
+            WARN() << "page flip failed: " << errno << " " << strerror(errno);
         }
         mPending = mDrawing;
         mDrawing = nullptr;
@@ -584,10 +599,7 @@ GLuint DisplayOzone::makeShader(GLuint type, const char *src)
     gl->getShaderiv(shader, GL_COMPILE_STATUS, &compiled);
     if (compiled != GL_TRUE)
     {
-        // This code is solely for internal debugging of shaders in drawWithTexture(),
-        // used when putting pixels on screen when running tests on ChromeOS device.
-        // Error will not propagate beyond ASSERT(linked) there.
-        ERR() << "DisplayOzone shader compilation error: " << buf;
+        WARN() << "DisplayOzone shader compilation error: " << buf;
     }
 
     return shader;
@@ -642,7 +654,11 @@ void DisplayOzone::drawWithTexture(Buffer *buffer)
         gl->linkProgram(mProgram);
         GLint linked;
         gl->getProgramiv(mProgram, GL_LINK_STATUS, &linked);
-        ASSERT(linked);
+        if (!linked)
+        {
+            WARN() << "shader link failed: cannot display buffer";
+            return;
+        }
         mCenterUniform     = gl->getUniformLocation(mProgram, "center");
         mWindowSizeUniform = gl->getUniformLocation(mProgram, "windowSize");
         mBorderSizeUniform = gl->getUniformLocation(mProgram, "borderSize");
@@ -819,7 +835,11 @@ void DisplayOzone::terminate()
         SafeDelete(mEGL);
     }
 
+    drmModeFreeConnector(mConnector);
+    mConnector = nullptr;
+    mMode      = nullptr;
     drmModeFreeCrtc(mCRTC);
+    mCRTC = nullptr;
 
     if (mGBM)
     {

src/libANGLE/renderer/gl/egl/ozone/DisplayOzone.h

@@ -152,6 +152,7 @@ class DisplayOzone final : public DisplayEGL
     void drawWithBlit(Buffer *buffer);
     void drawWithTexture(Buffer *buffer);
     void flushGL();
+    bool hasUsableScreen(int fd);
     void presentScreen();
     static void pageFlipHandler(int fd,
                                 unsigned int sequence,