On Sun, Mar 07, 2021 at 05:52:19PM +0100, Matthias Schwarzott wrote:

This time Kindle is sde again:

# dmesg |tail
[83709.973141] usb-storage 3-4:1.0: USB Mass Storage device detected
[83709.973226] scsi host8: usb-storage 3-4:1.0
[83711.028665] scsi 8:0:0:0: Direct-Access     Kindle   Internal Storage
0100 PQ: 0 ANSI: 2
[83711.028792] sd 8:0:0:0: Attached scsi generic sg5 type 0
[83711.031536] sd 8:0:0:0: Power-on or device reset occurred
[83711.046604] sd 8:0:0:0: [sde] Attached SCSI removable disk
[83713.145467] sd 8:0:0:0: [sde] 6688768 512-byte logical blocks: (3.42
GB/3.19 GiB)
[83713.364900] sd 8:0:0:0: [sde] Write cache: enabled, read cache: enabled,
doesn't support DPO or FUA
[83713.364906] sde: detected capacity change from 0 to 6688768
[83713.368036]  sde: sde1
# cat /sys/block/sde/device/power/control
on

power/control reports the same value for all sd? devices on this system.

Okay.  Can you collect a usbmon trace showing the events leading up to 
and including a disconnection?

Alan Stern

PS: I suspect the SYNCHRONIZE CACHE commands are correlated with the 
disconnections but don't cause them.  That is, I suspect the 
disconnections happen when the device has been idle -- and generally the 
host computer sends a SYNCHRONIZE CACHE command before idling a 
removable drive.