Bug#782442: USB3 external HDD not recognized [regression]

[Ralf Jung <post@ralfj.de>]

Hi,

> Attached a testpatch based on 4.1-rc2

Thanks. Unfortunately, this patch did not help: I saw no change in
behavior compared to vanilla 4.1-rc2.

I should probably mention that there is a slight difference in the log
output of the 3.16 and 4.1 kernels: The "xhci_hcd 0000:04:00.0: irq 42
for MSI/MSI-X" messages only show up with the older kernels.

>> ACTION=="add", SUBSYSTEM=="pci", ATTR{power/control}="auto"
>>
>> Sorry that I forgot to mention this.
> 
> No worries, we need to get the usb3 drive detected even if the controller is in runtime suspend.

Indeed doing "echo 'on' | sudo tee /sys/bus/pci/devices/*/power/control"
fixes the problem: When I subsequently plug in the disk, it is
recognized correctly. I confirmed this with an older kernel (the 3.16
Debian kernel, to be more precise). That's good to know, now I don't
need to reboot to a different kernel anymore to do fast backups ;-)

Kind regards,
Ralf