I recently replaced the motherboard on my desktop with an MSI B450-A
Pro Max motherboard. Since then my keybaords, mouse and tablet have
become very unreliable. I see messages like this over and over in
dmesg:
ug 23 00:01:49 rhapsody kernel: [198769.314732] usb 1-2.4: reset full-speed USB
device number 27 using ehci-pci
Aug 23 00:01:49 rhapsody kernel: [198769.562234] usb 1-2.1: reset full-speed USB
device number 28 using ehci-pci
Aug 23 00:01:52 rhapsody kernel: [198772.570704] usb 1-2.1: reset full-speed USB
device number 28 using ehci-pci
Aug 23 00:02:02 rhapsody kernel: [198782.526669] usb 1-2.4: reset full-speed USB
device number 27 using ehci-pci
Aug 23 00:02:03 rhapsody kernel: [198782.714660] usb 1-2.1: reset full-speed USB
device number 28 using ehci-pci
Aug 23 00:02:04 rhapsody kernel: [198784.210171] usb 1-2.3: reset low-speed USB device number 26 using ehci-pci
Aug 23 00:02:06 rhapsody kernel: [198786.110181] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
Aug 23 00:02:08 rhapsody kernel: [198787.726158] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
Aug 23 00:02:10 rhapsody kernel: [198790.126628] usb 1-2.1: reset full-speed USB device number 28 using ehci-pci
Aug 23 00:02:10 rhapsody kernel: [198790.314141] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
Aug 23 00:02:12 rhapsody kernel: [198792.518765] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
The devices I am using are:
- Logitech K360 wireless keyboard
- Wired Lenovo USB keyboard
- Wired Lenovo USB mouse
- Wired Wacom Intuos tablet
After a reset, the wireless keyboard simply stops working. Rest of
the devices keep seeing intermittent failure.
I tried various combinations of hubs and USB controllers to see what
works. MSI B450-A motherboard has USB 3.0 and USB 3.1 controllers. I
added a USB 2.0 PCI card as well for this test:
03:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset USB 3.1 XHCI Controller (rev 01)
29:01.0 USB controller: NEC Corporation OHCI USB Controller (rev 43)
29:01.1 USB controller: NEC Corporation OHCI USB Controller (rev 43)
29:01.2 USB controller: NEC Corporation uPD72010x USB 2.0 Controller (rev 04)
2c:00.3 USB controller: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller
I have a bus powered USB 3.0 hub, a bus powered USB 2.0 hub and a
self powered USB 2.0 hub built into my monitor.
I have connected my devices directly into the ports on motherboard
and PCI card as well as into external hub. Here are the results I
saw when devices wee plugged into various combination of ports:
1. USB 3.0/3.1 controller - does NOT work
2. USB 2.0 controller - WORKS
3. USB 3.0/3.1 controller -> Self powered USB 2.0 hub in monitor - does
NOT work
4. USB 3.0/3.1 controller -> bus powered USB 3.0 hub - does NOT work
5. USB 3.0/3.1 controller -> Bus powered USB 2.0 hub - WORKS
7. USB 2.0 controller -> Bus powered USB 3.0 hub - does NOT work
8. USB 2.0 controller -> Bus powered 2.0 hub - Does not work
I narrowed the failure down to following lines (this code was added
in 5.5 with commit 64cc3f12d1c7 "USB: EHCI: Do not return -EPIPE
when hub is disconnected"):
drivers/usb/host/ehci-q.c:
217 } else if ((token & QTD_STS_MMF) &&
218 (QTD_PID(token) == PID_CODE_IN)) {
219 status = -EPROTO;
220 /* CERR nonzero + halt --> stall */
At the time of failure, when we reach this conditional, token is
either 0x80408d46 or 0x408d46 which means following bits are set:
QTD_STS_STS, QTD_STS_MMF, QTD_STS_HALT, QTD_IOC, QTD_TOGGLE
and
QTD_PID = 1
QTD_CERR = 3
QTD_LENGTH = 0x40 (64)
This causes the branch "(token & QTD_STS_MMF) && (QTD_PID(token) ==
PID_CODE_IN" to be taken and qtd_copy_status() returns EPROTO. This
return value in qh_completions() results in ehci_clear_tt_buffer()
being called:
drivers/usb/host/ehci-q.c:
472 /* As part of low/full-speed endpoint-halt processi ng
473 * we must clear the TT buffer (11.17.5).
474 */
475 if (unlikely(last_status != -EINPROGRESS &&
476 last_status != -EREMOTEIO)) {
477 /* The TT's in some hubs malfunction when t hey
478 * receive this request following a STALL ( they
479 * stop sending isochronous packets). Sinc e a
480 * STALL can't leave the TT buffer in a bus y
481 * state (if you believe Figures 11-48 - 11 -51
482 * in the USB 2.0 spec), we won't clear the TT
483 * buffer in this case. Strictly speaking this
484 * is a violation of the spec.
485 */
486 if (last_status != -EPIPE)
487 ehci_clear_tt_buffer(ehci, qh, urb,
488 token);
489 }
It seems like clearing TT buffers in this case is resulting in hub
hanging. A USB reset gets it going again until we repeat the cycle
over again. The comment in this code says "The TT's in some hubs
malfunction when they receive this request following a STALL (they
stop sending isochronous packets)". That may be what is happening.
Removing the code that returns EPROTO for such case solves the
problem on my machine (as in the RFC patch) but that probably is not
the right solution. I do not understand USB protocol well enough to
propose a better solution. Does anyone have a better idea?
Khalid Aziz (1):
usb: ehci: Remove erroneous return of EPROTO upon detection of stall
drivers/usb/host/ehci-q.c | 4 ----
1 file changed, 4 deletions(-)
--
2.25.1
On Mon, Aug 31, 2020 at 10:23:30AM -0600, Khalid Aziz wrote:
> [Resending since I screwed up linux-usb mailing list address in
> cut-n-paste in original email]
>
>
> I recently replaced the motherboard on my desktop with an MSI B450-A
> Pro Max motherboard. Since then my keybaords, mouse and tablet have
> become very unreliable. I see messages like this over and over in
> dmesg:
>
> ug 23 00:01:49 rhapsody kernel: [198769.314732] usb 1-2.4: reset full-speed USB
> device number 27 using ehci-pci
> Aug 23 00:01:49 rhapsody kernel: [198769.562234] usb 1-2.1: reset full-speed USB
> device number 28 using ehci-pci
> Aug 23 00:01:52 rhapsody kernel: [198772.570704] usb 1-2.1: reset full-speed USB
> device number 28 using ehci-pci
> Aug 23 00:02:02 rhapsody kernel: [198782.526669] usb 1-2.4: reset full-speed USB
> device number 27 using ehci-pci
> Aug 23 00:02:03 rhapsody kernel: [198782.714660] usb 1-2.1: reset full-speed USB
> device number 28 using ehci-pci
> Aug 23 00:02:04 rhapsody kernel: [198784.210171] usb 1-2.3: reset low-speed USB device number 26 using ehci-pci
> Aug 23 00:02:06 rhapsody kernel: [198786.110181] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
> Aug 23 00:02:08 rhapsody kernel: [198787.726158] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
> Aug 23 00:02:10 rhapsody kernel: [198790.126628] usb 1-2.1: reset full-speed USB device number 28 using ehci-pci
> Aug 23 00:02:10 rhapsody kernel: [198790.314141] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
> Aug 23 00:02:12 rhapsody kernel: [198792.518765] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
>
> The devices I am using are:
>
> - Logitech K360 wireless keyboard
> - Wired Lenovo USB keyboard
> - Wired Lenovo USB mouse
> - Wired Wacom Intuos tablet
>
> After a reset, the wireless keyboard simply stops working. Rest of
> the devices keep seeing intermittent failure.
>
> I tried various combinations of hubs and USB controllers to see what
> works. MSI B450-A motherboard has USB 3.0 and USB 3.1 controllers. I
> added a USB 2.0 PCI card as well for this test:
>
> 03:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset USB 3.1 XHCI Controller (rev 01)
> 29:01.0 USB controller: NEC Corporation OHCI USB Controller (rev 43)
> 29:01.1 USB controller: NEC Corporation OHCI USB Controller (rev 43)
> 29:01.2 USB controller: NEC Corporation uPD72010x USB 2.0 Controller (rev 04)
> 2c:00.3 USB controller: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller
>
> I have a bus powered USB 3.0 hub, a bus powered USB 2.0 hub and a
> self powered USB 2.0 hub built into my monitor.
>
> I have connected my devices directly into the ports on motherboard
> and PCI card as well as into external hub. Here are the results I
> saw when devices wee plugged into various combination of ports:
>
> 1. USB 3.0/3.1 controller - does NOT work
> 2. USB 2.0 controller - WORKS
> 3. USB 3.0/3.1 controller -> Self powered USB 2.0 hub in monitor - does
> NOT work
> 4. USB 3.0/3.1 controller -> bus powered USB 3.0 hub - does NOT work
> 5. USB 3.0/3.1 controller -> Bus powered USB 2.0 hub - WORKS
> 7. USB 2.0 controller -> Bus powered USB 3.0 hub - does NOT work
> 8. USB 2.0 controller -> Bus powered 2.0 hub - Does not work
The error messages in your log extract all refer to ehci-pci, which is
the driver for a USB-2 controller. They are completely unrelated to any
problems you may be having with USB-3 controllers.
> I narrowed the failure down to following lines (this code was added
> in 5.5 with commit 64cc3f12d1c7 "USB: EHCI: Do not return -EPIPE
> when hub is disconnected"):
>
> drivers/usb/host/ehci-q.c:
>
> 217 } else if ((token & QTD_STS_MMF) &&
> 218 (QTD_PID(token) == PID_CODE_IN)) {
> 219 status = -EPROTO;
> 220 /* CERR nonzero + halt --> stall */
>
> At the time of failure, when we reach this conditional, token is
> either 0x80408d46 or 0x408d46 which means following bits are set:
>
> QTD_STS_STS, QTD_STS_MMF, QTD_STS_HALT, QTD_IOC, QTD_TOGGLE
>
> and
>
> QTD_PID = 1
> QTD_CERR = 3
> QTD_LENGTH = 0x40 (64)
>
> This causes the branch "(token & QTD_STS_MMF) && (QTD_PID(token) ==
> PID_CODE_IN" to be taken and qtd_copy_status() returns EPROTO. This
> return value in qh_completions() results in ehci_clear_tt_buffer()
> being called:
>
> drivers/usb/host/ehci-q.c:
> 472 /* As part of low/full-speed endpoint-halt processi ng
> 473 * we must clear the TT buffer (11.17.5).
> 474 */
> 475 if (unlikely(last_status != -EINPROGRESS &&
> 476 last_status != -EREMOTEIO)) {
> 477 /* The TT's in some hubs malfunction when t hey
> 478 * receive this request following a STALL ( they
> 479 * stop sending isochronous packets). Sinc e a
> 480 * STALL can't leave the TT buffer in a bus y
> 481 * state (if you believe Figures 11-48 - 11 -51
> 482 * in the USB 2.0 spec), we won't clear the TT
> 483 * buffer in this case. Strictly speaking this
> 484 * is a violation of the spec.
> 485 */
> 486 if (last_status != -EPIPE)
> 487 ehci_clear_tt_buffer(ehci, qh, urb,
> 488 token);
> 489 }
>
> It seems like clearing TT buffers in this case is resulting in hub
> hanging. A USB reset gets it going again until we repeat the cycle
> over again. The comment in this code says "The TT's in some hubs
> malfunction when they receive this request following a STALL (they
> stop sending isochronous packets)". That may be what is happening.
What makes you think that? Do you have any evidence that the hub is
receiving a STALL? Indeed, the commit you referenced above specifically
mentions that when MMF is set and the PID code is IN then it is not a
STALL.
> Removing the code that returns EPROTO for such case solves the
> problem on my machine (as in the RFC patch)
It certainly can't solve the problem for any USB-3 connections, because
the patch doesn't touch any of the USB-3 driver code.
> but that probably is not
> the right solution. I do not understand USB protocol well enough to
> propose a better solution. Does anyone have a better idea?
Can you collect a usbmon trace showing an example of this problem?
One possibility is to introduce a special quirk for the NEC uPD72010x
EHCI controller. But we should hold off on that until we know exactly
what is happening.
Alan Stern
On 8/31/20 8:31 PM, Alan Stern wrote:
> On Mon, Aug 31, 2020 at 10:23:30AM -0600, Khalid Aziz wrote:
>> [Resending since I screwed up linux-usb mailing list address in
>> cut-n-paste in original email]
>>
>>
>> I recently replaced the motherboard on my desktop with an MSI B450-A
>> Pro Max motherboard. Since then my keybaords, mouse and tablet have
>> become very unreliable. I see messages like this over and over in
>> dmesg:
>>
>> ug 23 00:01:49 rhapsody kernel: [198769.314732] usb 1-2.4: reset full-speed USB
>> device number 27 using ehci-pci
>> Aug 23 00:01:49 rhapsody kernel: [198769.562234] usb 1-2.1: reset full-speed USB
>> device number 28 using ehci-pci
>> Aug 23 00:01:52 rhapsody kernel: [198772.570704] usb 1-2.1: reset full-speed USB
>> device number 28 using ehci-pci
>> Aug 23 00:02:02 rhapsody kernel: [198782.526669] usb 1-2.4: reset full-speed USB
>> device number 27 using ehci-pci
>> Aug 23 00:02:03 rhapsody kernel: [198782.714660] usb 1-2.1: reset full-speed USB
>> device number 28 using ehci-pci
>> Aug 23 00:02:04 rhapsody kernel: [198784.210171] usb 1-2.3: reset low-speed USB device number 26 using ehci-pci
>> Aug 23 00:02:06 rhapsody kernel: [198786.110181] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
>> Aug 23 00:02:08 rhapsody kernel: [198787.726158] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
>> Aug 23 00:02:10 rhapsody kernel: [198790.126628] usb 1-2.1: reset full-speed USB device number 28 using ehci-pci
>> Aug 23 00:02:10 rhapsody kernel: [198790.314141] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
>> Aug 23 00:02:12 rhapsody kernel: [198792.518765] usb 1-2.4: reset full-speed USB device number 27 using ehci-pci
>>
>> The devices I am using are:
>>
>> - Logitech K360 wireless keyboard
>> - Wired Lenovo USB keyboard
>> - Wired Lenovo USB mouse
>> - Wired Wacom Intuos tablet
>>
>> After a reset, the wireless keyboard simply stops working. Rest of
>> the devices keep seeing intermittent failure.
>>
>> I tried various combinations of hubs and USB controllers to see what
>> works. MSI B450-A motherboard has USB 3.0 and USB 3.1 controllers. I
>> added a USB 2.0 PCI card as well for this test:
>>
>> 03:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset USB 3.1 XHCI Controller (rev 01)
>> 29:01.0 USB controller: NEC Corporation OHCI USB Controller (rev 43)
>> 29:01.1 USB controller: NEC Corporation OHCI USB Controller (rev 43)
>> 29:01.2 USB controller: NEC Corporation uPD72010x USB 2.0 Controller (rev 04)
>> 2c:00.3 USB controller: Advanced Micro Devices, Inc. [AMD] Matisse USB 3.0 Host Controller
>>
>> I have a bus powered USB 3.0 hub, a bus powered USB 2.0 hub and a
>> self powered USB 2.0 hub built into my monitor.
>>
>> I have connected my devices directly into the ports on motherboard
>> and PCI card as well as into external hub. Here are the results I
>> saw when devices wee plugged into various combination of ports:
>>
>> 1. USB 3.0/3.1 controller - does NOT work
>> 2. USB 2.0 controller - WORKS
>> 3. USB 3.0/3.1 controller -> Self powered USB 2.0 hub in monitor - does
>> NOT work
>> 4. USB 3.0/3.1 controller -> bus powered USB 3.0 hub - does NOT work
>> 5. USB 3.0/3.1 controller -> Bus powered USB 2.0 hub - WORKS
>> 7. USB 2.0 controller -> Bus powered USB 3.0 hub - does NOT work
>> 8. USB 2.0 controller -> Bus powered 2.0 hub - Does not work
>
> The error messages in your log extract all refer to ehci-pci, which is
> the driver for a USB-2 controller. They are completely unrelated to any
> problems you may be having with USB-3 controllers.
I just happened to cut and paste the messages from when I was testing
with the USB 2.0 controller. Here are the messages when I ran the test
with USB 3.0 controller:
Aug 13 14:25:48 rhapsody kernel: [78779.868354] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:26:18 rhapsody kernel: [78809.939457] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:26:39 rhapsody kernel: [78830.899982] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:26:39 rhapsody kernel: [78831.379883] usb 1-9.2: reset
low-speed USB device number 36 using xhci_hcd
Aug 13 14:26:40 rhapsody kernel: [78832.043900] usb 1-9.3: reset
low-speed USB device number 37 using xhci_hcd
Aug 13 14:26:47 rhapsody kernel: [78839.520211] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:26:49 rhapsody kernel: [78841.035843] usb 1-9.2: reset
low-speed USB device number 36 using xhci_hcd
Aug 13 14:26:50 rhapsody kernel: [78841.695837] usb 1-9.3: reset
low-speed USB device number 37 using xhci_hcd
Aug 13 14:27:57 rhapsody kernel: [78909.299772] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:27:58 rhapsody kernel: [78909.779179] usb 1-9.2: reset
low-speed USB device number 36 using xhci_hcd
Aug 13 14:28:05 rhapsody kernel: [78916.650851] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:32:02 rhapsody kernel: [79153.986777] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:32:22 rhapsody kernel: [79173.898757] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
Aug 13 14:32:23 rhapsody kernel: [79175.174206] usb 1-9.3: reset
low-speed USB device number 37 using xhci_hcd
Aug 13 14:32:24 rhapsody kernel: [79175.833619] usb 1-9.2: reset
low-speed USB device number 36 using xhci_hcd
Aug 13 14:34:23 rhapsody kernel: [79295.230293] usb 1-9.4: reset
full-speed USB device number 38 using xhci_hcd
>
>> I narrowed the failure down to following lines (this code was added
>> in 5.5 with commit 64cc3f12d1c7 "USB: EHCI: Do not return -EPIPE
>> when hub is disconnected"):
>>
>> drivers/usb/host/ehci-q.c:
>>
>> 217 } else if ((token & QTD_STS_MMF) &&
>> 218 (QTD_PID(token) == PID_CODE_IN)) {
>> 219 status = -EPROTO;
>> 220 /* CERR nonzero + halt --> stall */
>>
>> At the time of failure, when we reach this conditional, token is
>> either 0x80408d46 or 0x408d46 which means following bits are set:
>>
>> QTD_STS_STS, QTD_STS_MMF, QTD_STS_HALT, QTD_IOC, QTD_TOGGLE
>>
>> and
>>
>> QTD_PID = 1
>> QTD_CERR = 3
>> QTD_LENGTH = 0x40 (64)
>>
>> This causes the branch "(token & QTD_STS_MMF) && (QTD_PID(token) ==
>> PID_CODE_IN" to be taken and qtd_copy_status() returns EPROTO. This
>> return value in qh_completions() results in ehci_clear_tt_buffer()
>> being called:
>>
>> drivers/usb/host/ehci-q.c:
>> 472 /* As part of low/full-speed endpoint-halt processi ng
>> 473 * we must clear the TT buffer (11.17.5).
>> 474 */
>> 475 if (unlikely(last_status != -EINPROGRESS &&
>> 476 last_status != -EREMOTEIO)) {
>> 477 /* The TT's in some hubs malfunction when t hey
>> 478 * receive this request following a STALL ( they
>> 479 * stop sending isochronous packets). Sinc e a
>> 480 * STALL can't leave the TT buffer in a bus y
>> 481 * state (if you believe Figures 11-48 - 11 -51
>> 482 * in the USB 2.0 spec), we won't clear the TT
>> 483 * buffer in this case. Strictly speaking this
>> 484 * is a violation of the spec.
>> 485 */
>> 486 if (last_status != -EPIPE)
>> 487 ehci_clear_tt_buffer(ehci, qh, urb,
>> 488 token);
>> 489 }
>>
>> It seems like clearing TT buffers in this case is resulting in hub
>> hanging. A USB reset gets it going again until we repeat the cycle
>> over again. The comment in this code says "The TT's in some hubs
>> malfunction when they receive this request following a STALL (they
>> stop sending isochronous packets)". That may be what is happening.
>
> What makes you think that? Do you have any evidence that the hub is
> receiving a STALL? Indeed, the commit you referenced above specifically
> mentions that when MMF is set and the PID code is IN then it is not a
> STALL.
>
You are probably right about that. I do not understand USB protocol well
enough. Eliminating clearing TT buffers when split transaction is
incomplete fixed the problem for me. If I changed qtd_copy_status() to
return EPIPE as it was doing before commit 64cc3f12d1c7, USB resets went
away on my machine, so I am wondering if the comment at
drivers/usb/host/ehci-q.c:477 is applicable here.
>> Removing the code that returns EPROTO for such case solves the
>> problem on my machine (as in the RFC patch)
>
> It certainly can't solve the problem for any USB-3 connections, because
> the patch doesn't touch any of the USB-3 driver code.
Right. It solves the problem I see with USB 2.0 controller. I continue
to see issues with USB 3.0 if I move the hub to a USB 3.0 port.
>
>> but that probably is not
>> the right solution. I do not understand USB protocol well enough to
>> propose a better solution. Does anyone have a better idea?
>
> Can you collect a usbmon trace showing an example of this problem?
Sure. I will do that. Tracing the code when debugging for USB 2.0
controller led me to that specific line of code. As I said, I do not
understand USB well enough to say if changing that code is the right
solution, and it indeed solves the problem for USB 2.0 only.
>
> One possibility is to introduce a special quirk for the NEC uPD72010x
> EHCI controller. But we should hold off on that until we know exactly
> what is happening.
I do not believe whatever is causing USB resets is unique to NEC chip. I
am seeing issues on the USB 3.0 controllers as well.
>
> Alan Stern
>
Thanks,
Khalid
On Tue, Sep 01, 2020 at 08:51:14AM -0700, Khalid Aziz wrote:
> >> At the time of failure, when we reach this conditional, token is
> >> either 0x80408d46 or 0x408d46 which means following bits are set:
> >>
> >> QTD_STS_STS, QTD_STS_MMF, QTD_STS_HALT, QTD_IOC, QTD_TOGGLE
> >>
> >> and
> >>
> >> QTD_PID = 1
> >> QTD_CERR = 3
> >> QTD_LENGTH = 0x40 (64)
> >>
> >> This causes the branch "(token & QTD_STS_MMF) && (QTD_PID(token) ==
> >> PID_CODE_IN" to be taken and qtd_copy_status() returns EPROTO. This
> >> return value in qh_completions() results in ehci_clear_tt_buffer()
> >> being called:
I didn't mention this before, but that combination of events doesn't
make sense. The MMF bit is supposed to get set only for queue heads in
the periodic list, that is, only for interrupt transactions. But
ehci_clear_tt_buffer() doesn't do anything for interrupt endpoints; it
tests specifically for that right at the start.
Maybe your EHCI controller is setting the MMF bit when it shouldn't.
The usbmon output will help clear this up.
Or maybe the hubs you are testing don't work right. That's the only
reason I can think of for the failures you see with the USB-3
controller; the way it operates is very different from the way EHCI
does.
Alan Stern