Hi folks,
I have an issue with my Amazon Kindle. Since some time the device
disconnects 2 seconds after a sync command sent via USB.
See also this matching bug report:
https://bugzilla.kernel.org/show_bug.cgi?id=203973
My current workaround is this udev-rule:
SUBSYSTEM=="block", ACTION=="add", ENV{DEVTYPE}=="disk",
ENV{ID_VENDOR}=="Kindle", RUN+="/bin/bash -c 'echo write\ through >
/sys/block/%k/queue/write_cache'"
But I like to find a proper solution.
I did various recordings of usb-traffic with wireshark on linux and windows.
On windows, the device does not disconnect after the "Synchronize Cache"
command.
One major difference I noticed looking at service answer time statistics:
Windows sends a lot more requests of type "Test Unit Ready".
* Windows: 6385 calls
* linux: 71 calls
After most of the "Synchronize Cache" commands on windows there was
directly a following "WRITE" command. It seems WRITE commands avoid the
disconnect.
But sending a plain "Synchronize Cache" under windows (8.1 and 10) does
not trigger the disconnect.
Windows:
1583 14.891478 host 1.6.1 USBMS 58 SCSI: Synchronize Cache(10) LUN: 0x00
(LBA: 0x00000000, Len: 0)
1584 14.891595 1.6.1 host USB 27 URB_BULK out
1585 14.891613 host 1.6.1 USB 27 URB_BULK in
1586 14.896866 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Synchronize
Cache(10)) (Good)
1589 15.687209 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1590 15.687353 1.6.1 host USB 27 URB_BULK out
1591 15.687358 host 1.6.1 USB 27 URB_BULK in
1592 15.687405 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1713 16.699689 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1714 16.699820 1.6.1 host USB 27 URB_BULK out
1715 16.699825 host 1.6.1 USB 27 URB_BULK in
1716 16.699915 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1717 17.709334 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1718 17.709547 1.6.1 host USB 27 URB_BULK out
1719 17.709552 host 1.6.1 USB 27 URB_BULK in
1720 17.709586 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1721 18.712864 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1722 18.713081 1.6.1 host USB 27 URB_BULK out
1723 18.713086 host 1.6.1 USB 27 URB_BULK in
1724 18.713148 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1741 19.735245 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1742 19.735410 1.6.1 host USB 27 URB_BULK out
1743 19.735415 host 1.6.1 USB 27 URB_BULK in
1744 19.735474 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1811 20.747477 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1812 20.747699 1.6.1 host USB 27 URB_BULK out
1813 20.747704 host 1.6.1 USB 27 URB_BULK in
1814 20.747766 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1905 21.755419 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1906 21.755579 1.6.1 host USB 27 URB_BULK out
1907 21.755584 host 1.6.1 USB 27 URB_BULK in
1908 21.755674 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
1911 22.769205 host 1.6.1 USBMS 58 SCSI: Test Unit Ready LUN: 0x00
1912 22.769355 1.6.1 host USB 27 URB_BULK out
1913 22.769360 host 1.6.1 USB 27 URB_BULK in
1914 22.769415 1.6.1 host USBMS 40 SCSI: Response LUN: 0x00 (Test Unit
Ready) (Good)
How can I get further on this topic?
Thanks
Matthias
linux:
===========================================================================
SCSI Service Antwortzeit - kindle-linux-copy.pcap:
Index Procedure Calls Min SRT (s) Max SRT (s) Avg SRT (s) Sum SRT (s)
---------------------------------------------------------------------------
SBC (disk)
Inquiry 18 1 0.000742 0.000742 0.000742 0.000742
Mode Sense(6) 26 6 0.104194 0.110284 0.108607
0.651640
Prevent/Allow Medium Removal 30 10 0.000115 0.015012
0.002431 0.024309
Read Capacity(10) 37 3 0.000631 0.001004 0.000835
0.002506
Read(10) 40 2200 0.000136 0.020928 0.002452 5.393555
Request Sense 3 27 0.000295 0.003102 0.001022
0.027604
Synchronize Cache(10) 53 6 0.000223 2.703190
0.654663 3.927976
Test Unit Ready 0 71 0.000081 0.007955 0.000816
0.057908
Write(10) 42 195 0.001204 0.236517 0.022452 4.378117
SBC (disk)
---------------------------------------------------------------------------
windows:
===========================================================================
SCSI Service Antwortzeit - Kindle-sideload-win81.pcapng:
Index Procedure Calls Min SRT (s) Max SRT (s) Avg SRT (s) Sum SRT (s)
---------------------------------------------------------------------------
SBC (disk)
Inquiry 18 6 0.001026 0.109327 0.055329 0.331972
Mode Select(6) 21 2 0.001499 0.002851 0.002175
0.004350
Mode Sense(6) 26 8 0.102380 0.116633 0.108400
0.867199
Prevent/Allow Medium Removal 30 9 0.000274 0.644009
0.072284 0.650556
Read Capacity(10) 37 51 0.000144 0.109027 0.009779
0.498711
Read(10) 40 1269 0.000537 0.107562 0.003026 3.840104
Request Sense 3 19 0.000461 0.001388 0.000889
0.016893
Start Stop Unit 27 1 0.001695 0.001695 0.001695
0.001695
Synchronize Cache(10) 53 7 0.000511 0.001765
0.001052 0.007362
Test Unit Ready 0 6385 0.000090 0.083883 0.000605
3.859785
Unknown-0x%02x 35 3 0.108739 0.111119 0.109720
0.329159
Write(10) 42 303 0.001117 0.257120 0.030089 9.117113
SBC (disk)
---------------------------------------------------------------------------
