Change setting method of the DRM device filename.

README.md

@@ -168,13 +168,26 @@ Comming soon. We are contributing to support this now. See: https://github.com/f
 
 ### Run Fluter app
 
-Wayland compositor (weston) must be running before running the program when you use the Wayland backend.
+#### Run with Wayland backend
+
+Wayland compositor (weston) must be running before running the program.
 
 ```Shell
 $ ./flutter-client ./sample/build/linux/x64/release/bundle
 ```
 
-#### Note
+#### Run with DRM backend
+
+You need to switch from GUI which is running X11 or Wayland to the Character User Interface (CUI). In addition, `FLUTTER_DRM_DEVICE` must be set properly. The default value is `/dev/dri/card0`.
+
+```Shell
+$ Ctrl + Alt + F3 # Switching to CUI
+$ FLUTTER_DRM_DEVICE="/dev/dri/card1" ./flutter-drm-backend ./sample/build/linux/x64/release/bundle
+```
+
+If you want to switch back from CUI to GUI, run `Ctrl + Alt + F2` keys in a terminal.
+
+##### Note
 You need to run this program by a user who has the permission to access the input devices(/dev/input/xxx), if you use the DRM backend. Generally, it is a root user or a user who belongs to an input group.
 
 ## 5. Settings of weston.ini file (Only when you use weston desktop-shell)

examples/flutter-drm-backend/README.md

@@ -10,3 +10,16 @@ $ cd build
 $ cmake -DUSER_PROJECT_PATH=examples/flutter-drm-backend ..
 $ make
 ```
+
+## Running Flutter app
+
+You need to switch from GUI which is running X11 or Wayland to the Character User Interface (CUI). In addition, `FLUTTER_DRM_DEVICE` must be set properly. The default value is `/dev/dri/card0`.
+
+```Shell
+$ Ctrl + Alt + F3 # Switching to CUI
+$ FLUTTER_DRM_DEVICE="/dev/dri/card1" ./flutter-drm-backend FLUTTER_BUNDLE_PATH
+```
+
+Note that replace `FLUTTER_BUNDLE_PATH` with the flutter bundle path you want to use like ./sample/build/linux/x64/release/bundle.
+
+If you want to switch back from CUI to GUI, run `Ctrl + Alt + F2` keys in a terminal.

src/flutter/shell/platform/linux_embedded/window/linuxes_window_drm.cc

@@ -13,7 +13,8 @@
 
 namespace flutter {
 
-static constexpr char kDrmDeviceFilename[] = "/dev/dri/card0";
+static constexpr char kFlutterDrmDeviceEnvironmentKey[] = "FLUTTER_DRM_DEVICE";
+static constexpr char kDrmDeviceDefaultFilename[] = "/dev/dri/card0";
 
 const libinput_interface LinuxesWindowDrm::kLibinputInterface = {
     .open_restricted = [](const char* path, int flags, void* user_data) -> int {
@@ -29,8 +30,7 @@ const libinput_interface LinuxesWindowDrm::kLibinputInterface = {
 
 LinuxesWindowDrm::LinuxesWindowDrm(FlutterWindowMode window_mode, int32_t width,
                                    int32_t height, bool show_cursor)
-    : display_valid_(false),
-      is_pending_cursor_add_event_(false) {
+    : display_valid_(false), is_pending_cursor_add_event_(false) {
   window_mode_ = window_mode;
   current_width_ = width;
   current_height_ = height;
@@ -97,7 +97,13 @@ bool LinuxesWindowDrm::DispatchEvent() {
 }
 
 bool LinuxesWindowDrm::CreateRenderSurface(int32_t width, int32_t height) {
-  native_window_ = std::make_unique<NativeWindowDrm>(kDrmDeviceFilename);
+  auto device_filename = std::getenv(kFlutterDrmDeviceEnvironmentKey);
+  if ((!device_filename) || (device_filename[0] == '\0')) {
+    LINUXES_LOG(WARNING) << kFlutterDrmDeviceEnvironmentKey
+                         << " is not set, use " << kDrmDeviceDefaultFilename;
+    device_filename = const_cast<char*>(kDrmDeviceDefaultFilename);
+  }
+  native_window_ = std::make_unique<NativeWindowDrm>(device_filename);
   if (!native_window_->IsValid()) {
     LINUXES_LOG(ERROR) << "Failed to create the native window";
     return false;