MC7455 not listed as usb device any more after reboot

[Dan Williams]

On Fri, 2017-03-17 at 11:57 +0000, Thomas Lang wrote:
> Hi all,
> perhaps you have seen this bug before. I’m using the MC7455 with a
> linux system after normal power cycle (unplugged power) the mc 7455
> can be found  with lsusb:
> 
> 
> 
> go at ubuntu:~$ lsusb
> 
> Bus 003 Device 003: ID 1199:9071 Sierra Wireless, Inc.
> 
> Bus 003 Device 002: ID 0438:7900 Advanced Micro Devices, Inc.
> 
> Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> 
> Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
> 
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> 
> If I do a reboot, the mc7455 is not listed anymore.
> 
> Any ideas what might be the problem?

That's probably an issue with system BIOS or the kernel's USB stack,
unfortunately.  You'd want to enable debugging in the kernel drivers
for your USB HCI and then figure out why the device fails to be
enumerated.  There may even be logging for that already, check "dmesg"
for lines including "ehci" (USB 2), "ochi" (USB 1), and "xhci" (USB 3)
when the device fails to appear; perhaps something will show up for "3-
4", eg:

kernel: usb 3-4: new high-speed USB device number 2 using xhci_hcd

but if that device then fails to enumerate itself, the kernel won't
show it in lsusb since it can't get any information from it.

In any case, this sounds like a USB stack issue.

Dan