Re: [PATCH] usbnet: prevent device rpm suspend in usbnet_probe function

[Alan Stern]

On Thu, 10 Nov 2016, Kai-Heng Feng wrote:

> Hi,
> 
> On Wed, Nov 9, 2016 at 8:32 PM, BjÃrn Mork <bjorn@xxxxxxx> wrote:
> > Oliver Neukum <oneukum@xxxxxxxx> writes:
> >
> >> On Tue, 2016-11-08 at 13:44 -0500, Alan Stern wrote:
> >>
> >>> These problems could very well be caused by running at SuperSpeed
> >>> (USB-3) instead of high speed (USB-2).
> 
> Yes, it's running at SuperSpeed, on a Kabylake laptop.
> 
> It does not have this issue on a Broadwell laptop, also running at SuperSpeed.
> 
> >>>
> >>> Is there any way to test what happens when the device is attached to
> >>> the computer by a USB-2 cable?  That would prevent it from operating at
> >>> SuperSpeed.
> 
> I recall old Intel PCH can change the USB host from XHCI to EHCI,
> newer PCH does not have this option.
> 
> Is there a way to force XHCI run at HighSpeed?

Yes, like I said above: Use a USB-2 cable instead of a USB-3 cable.

Alan Stern