recent usb2 regression

[Giorgos Keramidas]

After my last update to March 1 sources, uhci started going into
interrupt storm mode:

  $ vmstat -i
  interrupt                          total       rate
  irq1: atkbd0                        8676          1
  irq9: acpi0                        12412          2
  irq12: psm0                         5979          1
  irq14: ata0                       601562        136
  irq15: ata1                           69          0
  irq16: uhci0                   745625990     169191
  irq19: uhci3                        5906          1
  irq23: uhci2 ehci1                     1          0
  cpu0: timer                      8813127       1999
  irq256: hdac0                     116677         26
  irq258: re0                         2438          0
  cpu1: timer                      8804089       1997
  irq259: vgapci0                    20525          4
  Total                          764017451     173364

Setting hw.usb2.uhci.debug=1 I see many repeated messages like:

  Mar  5 10:06:39 foo kernel: uhci_interrupt:1453: uhci_interrupt: host controller halted
  Mar  5 10:06:39 foo kernel: uhci_dumpregs:691: usbus0 regs: cmd=0080, sts=0020, intr=000f, frnum=0072, flbase=010be1c8, sof=0040, portsc1=0080, portsc2=0080
  Mar  5 10:06:39 foo kernel: uhci_dump_qh:764: QH(0xc6251e00) at 0x01a51e02: h_next=0x01a79e82 e_next=0x00000001
  Mar  5 10:06:39 foo kernel: uhci_dump_qh:764: QH(0xc6279e80) at 0x01a79e82: h_next=0x01a76702 e_next=0x00000001
  Mar  5 10:06:39 foo kernel: uhci_dump_qh:764: QH(0xc6276700) at 0x01a76702: h_next=0x01a8b002 e_next=0x00000001
  Mar  5 10:06:39 foo kernel: uhci_dump_qh:764: QH(0xc628b000) at 0x01a8b002: h_next=0x00000001 e_next=0x01a77080

There are local changes in this src/ tree, but none of them seems
related to usb2 going crazy.  I am running an i386 kernel build from the
`KOBE' config file shown in the patch uploaded at:

  http://people.freebsd.org/~keramida/diff/gker.head.r189392.diff

usbconfig shows only my USB mouse attached at the time:

  # usbconfig      
  ugen5.1: <UHCI root HUB Intel> at usbus5, cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
  ugen6.1: <EHCI root HUB Intel> at usbus6, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON
  ugen0.1: <UHCI root HUB Intel> at usbus0, cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
  ugen1.1: <UHCI root HUB Intel> at usbus1, cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
  ugen2.1: <EHCI root HUB Intel> at usbus2, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON
  ugen3.1: <UHCI root HUB Intel> at usbus3, cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
  ugen4.1: <UHCI root HUB Intel> at usbus4, cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
  ugen4.2: <product 0x0003 Creative Labs> at usbus4, cfg=0 md=HOST spd=LOW (1.5Mbps) pwr=ON

Is this a known problem with kernels from March 1, or a new one?