debugging Linux下USB中断间隔的异常行为

fcwjkofz  于 2022-11-30  发布在  Linux
关注(0)|答案(1)|浏览(125)

我正在开发一个嵌入式系统的USB设备驱动程序，主机是Linux系统（目前是Ubuntu 21.04）。设备基于FPGA，一个SmartFusion 2。我正在使用pyusb测试我的设备，我用Wireshark + usbmon检查性能。
该设备运行在高速模式下，有几个端点，特别是一个中断IN端点.在这个端点上：

  • 描述符中的间隔设置为32时，我的设备每32 ms（stdev ~ 50 us）获取一次令牌。这是低速/全速设备所期望的，因此这里已经存在一些问题，但其他情况是可以接受的。
  • 在间隔设置为16（或更少）的情况下，我得到了高达4096 ms（stdev ~100 us）。非常破碎。

这些时间是独立于设备的，我可以重置设备并重新连接，与之前的4096 ms周期的对齐几乎是完美的。它们也独立于pyusb启动时间和超时设置，所以我认为这是由于linux USB主机驱动程序。
这正常吗？我该怎么调试？
如果需要，我可以发布一些Wireshark捕获的内容。
我的描述符在其他方面对我来说看起来还不错，但也许我错过了一些东西：

sudo lsusb -v

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               3.00
  bDeviceClass            9 Hub
  bDeviceSubClass         0 
  bDeviceProtocol         3 
  bMaxPacketSize0         9
  idVendor           0x1d6b Linux Foundation
  idProduct          0x0003 3.0 root hub
  bcdDevice            5.11
  iManufacturer           3 Linux 5.11.0-22-generic xhci-hcd
  iProduct                2 xHCI Host Controller
  iSerial                 1 0000:00:15.0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x001f
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower                0mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         9 Hub
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 Full speed (or root) hub
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval              12
        bMaxBurst               0
Hub Descriptor:
  bLength              12
  bDescriptorType      42
  nNbrPorts             7
  wHubCharacteristic 0x000a
    No power switching (usb 1.0)
    Per-port overcurrent protection
  bPwrOn2PwrGood       10 * 2 milli seconds
  bHubContrCurrent      0 milli Ampere
  bHubDecLat          0.0 micro seconds
  wHubDelay             0 nano seconds
  DeviceRemovable    0x00
 Hub Port Status:
   Port 1: 0000.02a0 5Gbps power Rx.Detect
   Port 2: 0000.02a0 5Gbps power Rx.Detect
   Port 3: 0000.02a0 5Gbps power Rx.Detect
   Port 4: 0000.02a0 5Gbps power Rx.Detect
   Port 5: 0000.02a0 5Gbps power Rx.Detect
   Port 6: 0000.02a0 5Gbps power Rx.Detect
   Port 7: 0000.02a0 5Gbps power Rx.Detect
Binary Object Store Descriptor:
  bLength                 5
  bDescriptorType        15
  wTotalLength       0x000f
  bNumDeviceCaps          1
  SuperSpeed USB Device Capability:
    bLength                10
    bDescriptorType        16
    bDevCapabilityType      3
    bmAttributes         0x02
      Latency Tolerance Messages (LTM) Supported
    wSpeedsSupported   0x0008
      Device can operate at SuperSpeed (5Gbps)
    bFunctionalitySupport   3
      Lowest fully-functional device speed is SuperSpeed (5Gbps)
    bU1DevExitLat          10 micro seconds
    bU2DevExitLat         512 micro seconds
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0001
  Self Powered

-- Other device --

-- Other device --

-- Other device --

Bus 001 Device 083: ID 1514:fff0 Actel CLICK USB bridge
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          255 Vendor Specific Class
  bDeviceSubClass       255 Vendor Specific Subclass
  bDeviceProtocol       255 Vendor Specific Protocol
  bMaxPacketSize0        64
  idVendor           0x1514 Actel
  idProduct          0xfff0 
  bcdDevice            0.01
  iManufacturer           1 MIT STARLab
  iProduct                2 CLICK USB bridge
  iSerial                 3 V0.1
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x002e
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xc0
      Self Powered
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           4
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              32
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              32
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval             255
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval             255
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass          255 Vendor Specific Class
  bDeviceSubClass       255 Vendor Specific Subclass
  bDeviceProtocol       255 Vendor Specific Protocol
  bMaxPacketSize0        64
  bNumConfigurations      1
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0001
  Self Powered

-- Other device --

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            9 Hub
  bDeviceSubClass         0 
  bDeviceProtocol         1 Single TT
  bMaxPacketSize0        64
  idVendor           0x1d6b Linux Foundation
  idProduct          0x0002 2.0 root hub
  bcdDevice            5.11
  iManufacturer           3 Linux 5.11.0-22-generic xhci-hcd
  iProduct                2 xHCI Host Controller
  iSerial                 1 0000:00:15.0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0019
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower                0mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         9 Hub
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 Full speed (or root) hub
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval              12
Hub Descriptor:
  bLength              11
  bDescriptorType      41
  nNbrPorts             9
  wHubCharacteristic 0x000a
    No power switching (usb 1.0)
    Per-port overcurrent protection
    TT think time 8 FS bits
  bPwrOn2PwrGood       10 * 2 milli seconds
  bHubContrCurrent      0 milli Ampere
  DeviceRemovable    0x00 0x03
  PortPwrCtrlMask    0xff 0xff
 Hub Port Status:
   Port 1: 0000.0503 highspeed power enable connect
   Port 2: 0000.0503 highspeed power enable connect <- *** My device ***
   Port 3: 0000.0503 highspeed power enable connect
   Port 4: 0000.0100 power
   Port 5: 0000.0100 power
   Port 6: 0000.0503 highspeed power enable connect
   Port 7: 0000.0103 power enable connect
   Port 8: 0000.0100 power
   Port 9: 0000.0100 power
can't get device qualifier: Resource temporarily unavailable
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0001
  Self Powered
debugging

1条答案

按热度按时间
wd2eg0qa

wd2eg0qa1#

原来我无法正确读取规格。描述符中的bInterval设置是实际时间间隔的2的幂。对于高速模式：
时间间隔= 2**（b间隔-1）* 0.125。
因此，对于bInterval = 16，测量值为4096 ms。
此外，如果更高版本的linux将bInterval的最大值设置为9，则bInterval的最大值为16，并在dmesg中输出一些内容：

[  693.295727] usb 1-1.1: config 1 interface 0 altsetting 0 endpoint 0x81 has an invalid bInterval 32, changing to 9

因此，bInterval = 9为32毫秒......如测量值所示。

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