Messages in this thread | | | Date | Tue, 13 Dec 2016 08:24:08 -0500 (EST) | From | Alan Stern <> | Subject | Re: [RFC][PATCH 5/5] usb: dwc2: Add a quirk to allow speed negotiation for Hisilicon Hi6220 |
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On Mon, 12 Dec 2016, John Stultz wrote:
> From: Chen Yu <chenyu56@huawei.com> > > The Hi6220's usb controller is limited in that it does not > support "Split Transactions", so it does not support communicating > with low-speed and full-speed devices behind a high-speed hub. > > Thus it requires a quirk so that we can manually drop the usb > speed when low/full-speed are attached, and bump back to high > speed when they are removed.
Just out of curiosity (I know nothing about this hardware), what happens if there is a high-speed hub plugged into the host controller and both a high-speed and a full-speed device plugged into the hub?
Do you end up forcing the high-speed device to run at full speed?
Alan Stern
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