flutter-pi: getting vblank timestamps sometimes fails or results in invalid timestamps

I am having the same issue as in https://github.com/ardera/flutter-pi/issues/16

That is, flutter-pi shows a blank screen when I try to start the app when the Pi is connected to this display: https://www.waveshare.com/10.1inch-HDMI-LCD-B-with-case.htm

Connecting the Raspberry Pi to an hp 1080p monitor, everything works fine, including the touch screen panel from the above Waveshare display, so I can control the app fine by touching the display when I pipe the image to the HP monitor.

I’m running flutter-pi on Raspberry Pi 4 with the latest version of Raspbian Buster Desktop. I’ve modified it to boot to command line and then running flutter-pi there. The Waveshare display works otherwise fine, I’m able to for example boot to chromium in kiosk-mode and run a Flutter for Web app on it fine.

Any ideas how to get the display to work on flutter-pi? My expertise on such hardware issues is limited so it’s a bit challenging to troubleshoot this one.

Here’s the log when starting the app from SSH:

pi@raspberrypi:~/flutter-pi/out $ ./flutter-pi /home/pi/uikit/flutter_assets
engine_argv[0] = ./flutter-pi
initializing display...
Finding a suitable DRM device, since none is given...
looking for a suitable DRM device from 2 available DRM devices...
  devices[0]:
    available nodes: DRM_NODE_PRIMARY,
    nodes[DRM_NODE_PRIMARY] = "/dev/dri/card1"
    bustype: DRM_BUS_PLATFORM
    businfo.fullname: /soc/gpu
    opening DRM device candidate at "/dev/dri/card1"...
    getting resources of DRM device candidate at "/dev/dri/card1"...
    flutter-pi chose "/dev/dri/card1" as its DRM device.
  devices[1]:
    available nodes: DRM_NODE_PRIMARY, DRM_NODE_RENDER
    nodes[DRM_NODE_PRIMARY] = "/dev/dri/card0"
    nodes[DRM_NODE_RENDER] = "/dev/dri/renderD128"
    bustype: DRM_BUS_PLATFORM
    businfo.fullname: /v3dbus/v3d@7ec04000
Finding a connected connector from 1 available connectors...
  connectors[0]: connected? yes, type: 0x0B (HDMI-A), 150mm x 100mm
Choosing DRM mode from 2 available modes...
  modes[0]: name: "1280x800", 1280x800p, 63Hz, type: 72, flags: 10
    this mode is preferred by DRM. (DRM_MODE_TYPE_PREFERRED)
  modes[1]: name: "1280x800", 1280x800p, 60Hz, type: 32, flags: 6
Display properties:
  1280 x 800, 63Hz
  150mm x 100mm
  pixel_ratio = 2.245614
Finding DRM encoder...
Creating GBM device
Querying EGL client extensions...
Getting EGL display for GBM device...
Initializing EGL...
Querying EGL display extensions...
Using display 0x5cc538 with EGL version 1.4
===================================
EGL information:
  version: 1.4
  vendor: "Mesa Project"
  client extensions: "EGL_EXT_device_base EGL_EXT_device_enumeration EGL_EXT_device_query EGL_EXT_platform_base EGL_KHR_client_get_all_proc_addresses EGL_EXT_client_extensions EGL_KHR_debug EGL_EXT_platform_wayland EGL_EXT_platform_x11 EGL_MESA_platform_gbm EGL_MESA_platform_surfaceless EGL_EXT_platform_device"
  display extensions: "EGL_ANDROID_blob_cache EGL_EXT_buffer_age EGL_EXT_image_dma_buf_import EGL_EXT_image_dma_buf_import_modifiers EGL_KHR_cl_event2 EGL_KHR_config_attribs EGL_KHR_create_context EGL_KHR_create_context_no_error EGL_KHR_fence_sync EGL_KHR_get_all_proc_addresses EGL_KHR_gl_colorspace EGL_KHR_gl_renderbuffer_image EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_3D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_image EGL_KHR_image_base EGL_KHR_image_pixmap EGL_KHR_no_config_context EGL_KHR_reusable_sync EGL_KHR_surfaceless_context EGL_EXT_pixel_format_float EGL_KHR_wait_sync EGL_MESA_configless_context EGL_MESA_drm_image EGL_MESA_image_dma_buf_export EGL_MESA_query_driver EGL_WL_bind_wayland_display "
===================================
Binding OpenGL ES API...
Choosing EGL config...
Finding EGL configs with appropriate attributes...
Creating EGL context...
Creating EGL window surface...
===================================
OpenGL ES information:
  version: "OpenGL ES 3.0 Mesa 19.2.0-rc1"
  shading language version: "OpenGL ES GLSL ES 3.00"
  vendor: "Broadcom"
  renderer: "V3D 4.2"
  extensions: "GL_EXT_blend_minmax GL_EXT_multi_draw_arrays GL_EXT_texture_format_BGRA8888 GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth24 GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_mapbuffer GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_stencil8 GL_OES_texture_3D GL_OES_texture_float GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_vertex_half_float GL_EXT_texture_sRGB_decode GL_OES_EGL_image GL_OES_depth_texture GL_OES_packed_depth_stencil GL_EXT_texture_type_2_10_10_10_REV GL_OES_get_program_binary GL_APPLE_texture_max_level GL_EXT_discard_framebuffer GL_EXT_read_format_bgra GL_EXT_frag_depth GL_NV_fbo_color_attachments GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_vertex_array_object GL_EXT_occlusion_query_boolean GL_EXT_texture_rg GL_EXT_unpack_subimage GL_NV_draw_buffers GL_NV_read_buffer GL_NV_read_depth GL_NV_read_depth_stencil GL_NV_read_stencil GL_EXT_draw_buffers GL_EXT_map_buffer_range GL_KHR_debug GL_KHR_texture_compression_astc_ldr GL_OES_depth_texture_cube_map GL_OES_required_internalformat GL_OES_surfaceless_context GL_EXT_color_buffer_float GL_EXT_sRGB_write_control GL_EXT_separate_shader_objects GL_EXT_shader_integer_mix GL_EXT_base_instance GL_EXT_compressed_ETC1_RGB8_sub_texture GL_EXT_draw_elements_base_vertex GL_EXT_texture_border_clamp GL_KHR_context_flush_control GL_OES_draw_elements_base_vertex GL_OES_texture_border_clamp GL_OES_texture_stencil8 GL_EXT_float_blend GL_KHR_no_error GL_KHR_texture_compression_astc_sliced_3d GL_OES_EGL_image_external_essl3 GL_MESA_shader_integer_functions GL_KHR_parallel_shader_compile GL_EXT_texture_query_lod "
===================================
Swapping buffers...
Locking front buffer...
getting new framebuffer for BO...
Setting CRTC...
Clearing current context...
finished display setup!
Initializing Application...
Initializing Plugin Registry...
[services-plugin] init.
[text_input] init.
[raw_keyboard] init.
[test-plugin] init.
[elm327plugin] elm_open: process doesn't have access to serial device "/dev/rfcomm0": No such file or directory
[elm327plugin] ELM327Plugin_init: ELM327 communication was not initialized successfully. elm327plugin won't supply any OBDII data. error code: No such file or directory
[elm327plugin] running pid query queue processor
[ERROR:engine/src/flutter/shell/platform/embedder/embedder_surface_gl.cc(107)] Could not create a resource context for async texture uploads. Expect degraded performance. Set a valid make_resource_current callback on FlutterOpenGLRendererConfig.
flutter: Observatory listening on http://127.0.0.1:35431/U7qsOz2kkTw=/
[ERROR:engine/src/flutter/shell/platform/embedder/embedder_surface_gl.cc(107)] Could not create a resource context for async texture uploads. Expect degraded performance. Set a valid make_resource_current callback on FlutterOpenGLRendererConfig.
flutter engine successfully started up.
Initializing Input devices...
  input device 0: path="/dev/input/event0"
      WaveShare WS170120, connected via USB. vendor: 0x0EEF, product: 0x0005, version: 0x0110
Running IO thread...
Running message loop...