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

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

Hi,

On Wed, Nov 9, 2016 at 8:32 PM, Bjørn Mork [off-list ref] wrote:

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Oliver Neukum [off-list ref] writes:

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On Tue, 2016-11-08 at 13:44 -0500, Alan Stern wrote:

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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.

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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