树莓派CM4上Pygame程序二次启动时出现闪烁问题

环境与操作背景 #

• 硬件：树莓派CM4
• 系统：Raspberry Pi Lite OS (Buster)
• 操作步骤：
  1. 手动安装X环境：

     sudo apt-get install --no-install-recommends xserver-xorg xinit x11-xserver-utils openbox
     

  2. 配置开机自启（添加至.bash_profile）：

     [[ -z $DISPLAY && $XDG_VTNR -eq 1 ]] && startx -- -nocursor
     

  3. 配置Openbox自启程序（编辑/etc/xdg/openbox/autostart）：

     # Disable any form of screen saver / screen blanking / power management
     xset s off
     xset s noblank
     xset -dpms
     
     # Allow quitting the X server with CTRL-ATL-Backspace
     setxkbmap -option terminate:ctrl_alt_bksp
     
     cd project_dir && python project.py
     

  4. Pygame核心代码：

     import pygame as pg
     
     class Game:
         def __init__(self):
             pg.init()
     
             self.__clock = pg.time.Clock()
     
             self.__window_size = (1024, 768)
             self.__project_size = (392, 291)
     
             self.screen = pg.display.set_mode(self.__window_size, pg.FULLSCREEN)
     
             self.blank_background = pg.transform.scale(pg.image.load("assets/default_background.png"),
                     self.__window_size).convert()
             self.grid_image = pg.transform.scale(pg.image.load("assets/new_project_thumb.png"),
                     self.__project_size).convert()
     
             self.project_selected = 0
     
             self.rect_pixels = 3
     
             self.grid_locations = self.calculate_grid_locations()
     
         def run(self) -> None:
             pg.mouse.set_visible(False)
     
             playing = True
     
             while playing:
                 events = pg.event.get()
     
                 button_event = None
     
                 self.screen.blit(self.blank_background, (0, 0))
     
                 for event in events:
                     if event.type == pg.KEYDOWN:
                         button_event = event.key
     
                 if button_event == pg.K_LEFT:
                     self.project_selected = max((self.project_selected - 1), 0)
     
                 if button_event == pg.K_RIGHT:
                     self.project_selected = min((self.project_selected + 1), 3)
     
                 if button_event == pg.K_ESCAPE:
                     playing = False
     
                 self.draw_menu()
                 pg.display.update()
                 self.__clock.tick(6)
     
         def draw_menu(self):
             for i in range(4):
                 if i == self.project_selected:
                     rect_loc = (self.grid_locations[i][0] - self.rect_pixels,
                                 self.grid_locations[i][1] - self.rect_pixels)
                     pg.draw.rect(self.screen,
                                  (237, 28, 36),
                                  pg.Rect(rect_loc,
                                          (self.__project_size[0] + self.rect_pixels * 2,
                                           self.__project_size[1] + self.rect_pixels * 2)))
     
                 self.screen.blit(self.grid_image, self.grid_locations[i])
                                                    
     
         def calculate_grid_locations(self):
             w=int((self.__window_size[0] - 2 * self.__project_size[0]) / 3)
             h=int((self.__window_size[1] - 2 * self.__project_size[1]) / 3)
     
             return [(w, h),
                     (w * 2 + self.__project_size[0], h),
                     (w, h * 2 + self.__project_size[1]),
                     (w * 2 + self.__project_size[0], h * 2 + self.__project_size[1])]
     
     if __name__ == "__main__":
         game = Game()
         game.run()
     

异常现象 #

开机自启时程序运行正常；但通过Ctrl-Alt-Backspace强制退出X服务器和程序后，直接在命令行执行python project.py重启，显示会间歇性闪烁。此问题仅在CM4上出现，Ubuntu笔记本无该现象。

可能原因与解决方案 #

1. X强制退出后的显示硬件状态残留 #

CM4的GPU帧缓冲区或显示缓存在强制退出X时未完全重置，导致Pygame重启时与残留状态冲突。

• 解决方案：
  • 退出X后先执行fbset -depth 24重置帧缓冲区，再启动程序；
  • 或重新初始化X环境：执行xinit -- -nocursor后再运行python project.py，模拟开机启动流程。

2. Pygame资源未正常释放 #

强制退出时，Pygame未正确释放GPU资源或重置驱动状态，导致重启时初始化不完整。

• 解决方案：
  • 在程序退出逻辑中添加显式资源释放：在run方法的playing = False后增加pg.quit()；
  • 启动程序前执行unset DISPLAY清除残留环境变量，再启动程序。

3. Openbox环境变量残留 #

Openbox启动时设置的X相关环境变量（如DISPLAY、XAUTHORITY）在强制退出后未清理，导致Pygame使用无效配置。

• 解决方案：
  • 退出X后执行source ~/.bash_profile重新加载环境变量，或注销重登后启动程序；
  • 显式指定显示端口：执行DISPLAY=:0 python project.py。

4. CM4硬件加速模式异常 #

开机自启时X会初始化CM4的硬件加速模块，强制退出后该模块未正确关闭，导致Pygame重启无法获取加速资源。

• 解决方案：
  • 编辑/boot/config.txt，确保dtoverlay=vc4-fkms-v3d配置启用（Buster默认可能未开启）；
  • 启动程序前执行vcgencmd display_power 1重置显示电源状态。

内容的提问来源于stack exchange，提问作者ZPears