Hello!

Meanwhile I found the culprit:

https://www.spinics.net/lists/linux-usb/msg141467.html
and
https://www.spinics.net/lists/linux-usb/msg141468.html

Especially the last change breaks things here completely. After removing them by 
the attached patch, problems are gone and device works again as expected (I tested 
with the original 24 kB bulk size which was horribly broken w/o the attached 
patch). This means: the additional repair steps are not just breaking things but 
are even unnecessary (it's working perfectly without those changes) here.


I tested with 2 USB 3.1 host controllers:

USB controller: Advanced Micro Devices, Inc. [AMD] Raven USB 3.1 (prog-if 30 [XHCI])

05:00.3 0c03: 1022:15e0 (prog-if 30 [XHCI])
         Subsystem: 1043:201f
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR- FastB2B- DisINTx+
         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- 
<MAbort- >SERR- <PERR- INTx-
         Latency: 0, Cache Line Size: 64 bytes
         Interrupt: pin D routed to IRQ 37
         Region 0: Memory at f7300000 (64-bit, non-prefetchable) [size=1M]
         Capabilities: [48] Vendor Specific Information: Len=08 <?>
         Capabilities: [50] Power Management version 3
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0+,D1-,D2-,D3hot+,D3cold+)
                 Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
         Capabilities: [64] Express (v2) Endpoint, MSI 00
                 DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <4us, L1 
unlimited
                         ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset- 
SlotPowerLimit 0.000W
                 DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
                         RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
                         MaxPayload 256 bytes, MaxReadReq 512 bytes
                 DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
                 LnkCap: Port #0, Speed 8GT/s, Width x16, ASPM L0s L1, Exit 
Latency L0s <64ns, L1 <1us
                         ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
                 LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
                         ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
                 LnkSta: Speed 8GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- 
BWMgmt- ABWMgmt-
                 DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR+, 
OBFF Not Supported
                          AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                 DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, 
OBFF Disabled
                          AtomicOpsCtl: ReqEn-
                 LnkSta2: Current De-emphasis Level: -3.5dB, 
EqualizationComplete-, EqualizationPhase1-
                          EqualizationPhase2-, EqualizationPhase3-, 
LinkEqualizationRequest-
         Capabilities: [a0] MSI: Enable- Count=1/8 Maskable- 64bit+
                 Address: 0000000000000000  Data: 0000
         Capabilities: [c0] MSI-X: Enable+ Count=8 Masked-
                 Vector table: BAR=0 offset=000fe000
                 PBA: BAR=0 offset=000ff000
         Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
         Kernel driver in use: xhci_hcd
         Kernel modules: xhci_pci

The 2. device on the same machine has the PCI-ID 1022:15e1


Another USB3.1 host device tested with was:
USB controller: Advanced Micro Devices, Inc. [AMD] X370 Series Chipset USB 3.1 
xHCI Controller (rev 02) (prog-if 30 [XHCI])

00:06.0 0c03: 1022:43b9 (rev 02) (prog-if 30 [XHCI])
         Subsystem: 1b21:1142
         Physical Slot: 6
         Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR+ FastB2B- DisINTx+
         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- 
<MAbort- >SERR- <PERR- INTx-
         Latency: 0, Cache Line Size: 64 bytes
         Interrupt: pin A routed to IRQ 29
         Region 0: Memory at febd0000 (64-bit, non-prefetchable) [size=32K]
         Capabilities: [50] MSI: Enable+ Count=1/8 Maskable- 64bit+
                 Address: 00000000fee0e000  Data: 4023
         Capabilities: [78] Power Management version 3
                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA 
PME(D0-,D1-,D2-,D3hot+,D3cold+)
                 Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
         Capabilities: [80] Express (v2) Legacy Endpoint, MSI 00
                 DevCap: MaxPayload 512 bytes, PhantFunc 0, Latency L0s <64ns, L1 <2us
                         ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
                 DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
                         RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
                         MaxPayload 128 bytes, MaxReadReq 512 bytes
                 DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr+ TransPend-
                 LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L0s L1, Exit Latency 
L0s <2us, L1 unlimited
                         ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
                 LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
                         ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
                 LnkSta: Speed 8GT/s, Width x4, TrErr- Train- SlotClk+ DLActive- 
BWMgmt- ABWMgmt-
                 DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR+, 
OBFF Not Supported
                          AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                 DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, 
OBFF Disabled
                          AtomicOpsCtl: ReqEn-
                 LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete+, 
EqualizationPhase1+
                          EqualizationPhase2-, EqualizationPhase3-, 
LinkEqualizationRequest-
         Kernel driver in use: xhci_hcd
         Kernel modules: xhci_pci


Please fix those changes or disable them for the mentioned devices or add an 
option to disable this additional alignment feature.


Thanks
Andreas