Need help debugging the kernel

[V10lator]

I need help debugging a kernel issue with a external harddrive.

Logs with UAS enabled:

[42765.910407] sd 20:0:0:0: [sdi] uas_cmd_cmplt ffff88001edd9680 tag 0, inflight: CMD IN 
[42765.910413] sd 20:0:0:0: [sdi] cmd cmplt err -71 
[42796.634368] sd 20:0:0:0: [sdi] uas_eh_abort_handler ffff88001edd9680 tag 0, inflight: CMD IN 
[42796.634481] sd 20:0:0:0: [sdi] uas_cmd_cmplt ffff88001edd9680 tag 0, inflight: CMD IN abort 
[42796.634494] sd 20:0:0:0: [sdi] cmd cmplt err -71 
[42799.630770] scsi host20: uas_eh_task_mgmt: ABORT TASK timed out 
[42799.630804] sd 20:0:0:0: uas_eh_device_reset_handler 
[42799.630812] scsi host20: uas_eh_task_mgmt: LOGICAL UNIT RESET: error already running a task 
[42799.630820] scsi host20: uas_eh_bus_reset_handler start 
[42799.631037] usb 9-2: stat urb: killed, stream 16 
[42799.631273] usb 9-2: stat urb: killed, stream 2 
[42799.631525] sd 20:0:0:0: [sdi] uas_data_cmplt ffff88001edd9680 tag 0, inflight: CMD abort 
[42799.631532] sd 20:0:0:0: [sdi] data cmplt err -2 stream 2 
[42799.631576] sd 20:0:0:0: [sdi] uas_zap_dead ffff88001edd9680 tag 0, inflight: CMD abort 
[42799.631589] sd 20:0:0:0: [sdi] abort completed 
[42799.734948] usb 9-2: reset SuperSpeed USB device number 12 using xhci_hcd 
[42799.750400] xhci_hcd 0000:01:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88021d9d3c00 
[42799.750405] xhci_hcd 0000:01:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88021d9d3c48 
[42799.750407] xhci_hcd 0000:01:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88021d9d3c90 
[42799.750409] xhci_hcd 0000:01:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88021d9d3cd8 
[42799.752798] scsi host20: uas_eh_bus_reset_handler success 
[42800.825568]  sdi: unknown partition table

With UAS disabled:

[  873.430504] irq event 46: bogus return value ffffff94 
[  873.430512] CPU: 2 PID: 0 Comm: BFS/2 Tainted: G        W  O  3.16.1 #2 
[  873.430514] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./870 Extreme3, BIOS P1.60 09/14/2010 
[  873.430516]  00000000ffffff94 ffffffff818967bc ffff8800c7aa0900 ffffffff810c0161 
[  873.430518]  0000000000000000 00000000ffffff94 00000000ffffff94 ffffffff810bdf52 
[  873.430521]  ffff8800c7aa0900 ffff8800c7aa098c ffff88022d810e80 00000000000000d1 
[  873.430523] Call Trace: 
[  873.430524]  <IRQ>  [<ffffffff818967bc>] ? dump_stack+0x4a/0x75 
[  873.430533]  [<ffffffff810c0161>] ? __report_bad_irq+0x21/0xc0 
[  873.430536]  [<ffffffff810bdf52>] ? handle_irq_event_percpu+0x92/0x100 
[  873.430538]  [<ffffffff810bdff7>] ? handle_irq_event+0x37/0x60 
[  873.430540]  [<ffffffff810c0816>] ? handle_edge_irq+0x76/0x140 
[  873.430543]  [<ffffffff8103b055>] ? handle_irq+0x15/0x40 
[  873.430546]  [<ffffffff8103a96f>] ? do_IRQ+0x4f/0x100 
[  873.430548]  [<ffffffff818a10aa>] ? common_interrupt+0x6a/0x6a 
[  873.430549]  <EOI>  [<ffffffff81042b20>] ? amd_e400_idle+0x40/0x100 
[  873.430554]  [<ffffffff810aff9f>] ? cpu_startup_entry+0x27f/0x2e0 
[  873.430556] handlers: 
[  873.430558] [<ffffffff8162c440>] xhci_msi_irq 
[  909.114529] xhci_hcd 0000:01:00.0: xHCI host not responding to stop endpoint command. 
[  909.114542] xhci_hcd 0000:01:00.0: Assuming host is dying, halting host. 
[  909.122101] xhci_hcd 0000:01:00.0: HC died; cleaning up 
[  909.122149] usb 9-2: USB disconnect, device number 2 
[  909.124505] sd 8:0:0:0: [sdh] Unhandled error code 
[  909.124513] sd 8:0:0:0: [sdh]  
[  909.124515] Result: hostbyte=0x01 driverbyte=0x00 
[  909.124518] sd 8:0:0:0: [sdh] CDB: 
[  909.124520] cdb[0]=0x28: 28 00 01 1f 13 a8 00 00 08 00 
[  909.124528] end_request: I/O error, dev sdh, sector 18813864 
[  910.156229] sd 8:0:0:0: [sdh] Synchronizing SCSI cache 
[  910.156295] sd 8:0:0:0: [sdh]  
[  910.156301] Result: hostbyte=0x01 driverbyte=0x00

If I attach the disc to the internal SATA bus (no USB) everything is fine.

More infos: http://forums.gentoo.org/viewtopic-p-7641090.html

I'm thankfull for any help!