Hi, folks,
I'm finding that when I connect either an nRF52-DK (PCA10040 2.1.0 2020.31) or an nRF52840-DK (PCA10056 2.0.1 2020.33) to Linux (Ubuntu 20.04.4 LTS) the board connects and disconnects repeatedly to the point where I can't even program a board. I seem to have to power cycle the board about a dozen times or so before it finally stabilizes.
This same setup works fine when I reboot my machine to Windows.
Thanks.
```
dmesg | tail -30
[593293.123638] Buffer I/O error on dev sda, logical block 21823, async page read
[593294.083898] usb 3-1.4.2-port1: Cannot enable. Maybe the USB cable is bad?
[593295.000210] usb 3-1.4.2-port1: Cannot enable. Maybe the USB cable is bad?
[593295.000717] usb 3-1.4.2-port1: attempt power cycle
[593296.240412] usb 3-1.4.2-port1: Cannot enable. Maybe the USB cable is bad?
[593297.152019] usb 3-1.4.2-port1: Cannot enable. Maybe the USB cable is bad?
[593297.152415] usb 3-1.4.2-port1: unable to enumerate USB device
[593518.199728] Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
[593520.190960] Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
[593520.194367] Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
[593594.587483] usb 3-1.4.2.1: new high-speed USB device number 122 using xhci_hcd
[593594.700531] usb 3-1.4.2.1: config 1 interface 1 altsetting 0 bulk endpoint 0x83 has invalid maxpacket 64
[593594.700539] usb 3-1.4.2.1: config 1 interface 1 altsetting 0 bulk endpoint 0x4 has invalid maxpacket 64
[593594.701091] usb 3-1.4.2.1: New USB device found, idVendor=1366, idProduct=1015, bcdDevice= 1.00
[593594.701099] usb 3-1.4.2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[593594.701104] usb 3-1.4.2.1: Product: J-Link
[593594.701109] usb 3-1.4.2.1: Manufacturer: SEGGER
[593594.701112] usb 3-1.4.2.1: SerialNumber: 000682295249
[593594.719489] cdc_acm 3-1.4.2.1:1.0: ttyACM1: USB ACM device
[593594.720800] usb-storage 3-1.4.2.1:1.3: USB Mass Storage device detected
[593594.721343] scsi host0: usb-storage 3-1.4.2.1:1.3
[593595.728528] scsi 0:0:0:0: Direct-Access SEGGER MSD Volume 1.00 PQ: 0 ANSI: 4
[593595.729267] sd 0:0:0:0: Attached scsi generic sg0 type 0
[593595.729616] sd 0:0:0:0: [sda] 21829 512-byte logical blocks: (11.2 MB/10.7 MiB)
[593595.729922] sd 0:0:0:0: [sda] Write Protect is off
[593595.729927] sd 0:0:0:0: [sda] Mode Sense: 0b 00 00 08
[593595.730262] sd 0:0:0:0: [sda] No Caching mode page found
[593595.730270] sd 0:0:0:0: [sda] Assuming drive cache: write through
[593595.747204] sda:
[593595.798780] sd 0:0:0:0: [sda] Attached SCSI removable disk
```
```
uname -srvmpio
Linux 5.4.0-104-generic #118-Ubuntu SMP Wed Mar 2 19:02:41 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
```
