我写了一个小程序，它生成4个音频流（正弦波）并将它们发送到4个声卡（每个声卡连接到树莓派3的USB端口）。
几秒钟后，pi完全冻结/崩溃。我必须重新启动Raspberry Pi。
只需3个音频流（和3个USB声卡），一切都按预期工作。
CPU负载实际上是正常的（用htop监控）。 4个CPU大约占30％。
但是在崩溃之前我可以在syslog中找到以下条目：
Oct 11 18:48:13 pi kernel: [ 51.983775] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=6 fsm=8 on transfer to device 4 ep 0x4
Oct 11 18:48:14 pi kernel: [ 52.415833] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=2 fsm=9 on transfer to device 7 ep 0x1
Oct 11 18:48:14 pi kernel: [ 52.991916] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=3 fsm=9 on transfer to device 4 ep 0x4
Oct 11 18:48:14 pi kernel: [ 53.135930] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=2 fsm=9 on transfer to device 4 ep 0x4
Oct 11 18:48:15 pi kernel: [ 53.268195] Transfer to device 4 endpoint 0x4 frame 1995 failed - FIQ reported NYET. Data may have been lost.
Oct 11 18:48:15 pi kernel: [ 53.423974] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=3 fsm=9 on transfer to device 7 ep 0x1
Oct 11 18:48:15 pi kernel: [ 53.567994] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=3 fsm=9 on transfer to device 4 ep 0x4
Oct 11 18:48:15 pi kernel: [ 53.712005] WARN::dwc_otg_hcd_handle_hc_fsm:2619: Unexpected state received on hc=3 fsm=9 on transfer to device 7 ep 0x1
我怀疑USB存在问题。
是否有任何工具可以帮助我监控USB端口？例如缓冲区，丢包，等等
系统日志消息的含义是什么？
任何提示都赞赏！