Am 05.03.21 um 20:14 schrieb Alan Stern:
On Fri, Mar 05, 2021 at 05:54:43PM +0100, Matthias Schwarzott wrote:
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
It's generally well known that Windows issues lots and lots of redundant
commands to USB storage drives.
Unless the Kindle advertises removable media, there doesn't seem to be
any real point to all those TEST UNIT READY commands. Unless they are
what prevents the disconnections...
This is kernel log from connecting:
[41709.248006] usb 3-4: new high-speed USB device number 6 using xhci_hcd
[41709.380015] usb 3-4: New USB device found, idVendor=1949,
idProduct=0004, bcdDevice= 1.00
[41709.380019] usb 3-4: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[41709.380021] usb 3-4: Product: Amazon Kindle
[41709.380022] usb 3-4: Manufacturer: Amazon
[41709.380023] usb 3-4: SerialNumber: REMOVED
[41709.493988] usb-storage 3-4:1.0: USB Mass Storage device detected
[41709.494080] scsi host6: usb-storage 3-4:1.0
[41710.510122] scsi 6:0:0:0: Direct-Access Kindle Internal Storage
0100 PQ: 0 ANSI: 2
[41710.510245] sd 6:0:0:0: Attached scsi generic sg3 type 0
[41710.513059] sd 6:0:0:0: Power-on or device reset occurred
[41710.526331] sd 6:0:0:0: [sdc] Attached SCSI removable disk
[41712.629152] sd 6:0:0:0: [sdc] 6688768 512-byte logical blocks: (3.42
GB/3.19 GiB)
[41712.846353] sd 6:0:0:0: [sdc] Write cache: enabled, read cache:
enabled, doesn't support DPO or FUA
[41712.846357] sdc: detected capacity change from 0 to 6688768
[41712.849499] sdc: sdc1
As it prints "Attached SCSI removable disk" the device advertises
removable media.
How can I get further on this topic?
Is runtime power management enabled? Maybe the Kindle disconnects
whenever the computer tries to suspend it. This typically happens 2
seconds after the last command was issued, which matches your
observations. If runtime PM is enabled, you can try disabling it.
I assume this means autosuspend is not used:
# cat /sys/block/sde/device/power/control
on
# lsusb:
[...]
Bus 003 Device 017: ID 1949:0004 Lab126, Inc. Amazon Kindle 3/4/Paperwhite
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x1949 Lab126, Inc.
idProduct 0x0004 Amazon Kindle 3/4/Paperwhite
bcdDevice 1.00
iManufacturer 1 Amazon
iProduct 2 Amazon Kindle
iSerial 3 REMOVED....
bNumConfigurations 1
OTG Descriptor:
bLength 3
bDescriptorType 9
bmAttributes 0x03
SRP (Session Request Protocol)
HNP (Host Negotiation Protocol)
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0023
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 4 Self-powered
bmAttributes 0xc0
Self Powered
MaxPower 2mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk-Only
iInterface 5 Mass Storage
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 1
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 0
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
bNumConfigurations 1
Device Status: 0x0001
Self Powered
Regards
Matthias
