Re: [PATCH] usb-core: Add MS_INTR_BINTERVAL USB quirk

From: Alan Stern
Date: Mon Mar 13 2017 - 21:44:50 EST


On Mon, 13 Mar 2017, Samuel Thibault wrote:

> Alan Stern, on dim. 12 mars 2017 21:40:33 -0400, wrote:
> > On Sun, 12 Mar 2017, Dave Mielke wrote:
> > > [quoted lines by Alan Stern on 2017/03/12 at 21:31 -0400]
> > >
> > > >A device's speed is only partially related to its USB version. A
> > > >USB-1.1 device can run at low speed or full speed. A USB-2 device can
> > > >run at low, full, or high speed. And a USB-3 device can run at low,
> > > >full, high, or Super speed.
> > >
> > > Yes, I did know this, so maybe I misunderstood what you were wondering about.
> > > Were you wondering why 64ms was too long?
> >
> > No, I was wondering why an HID device would run at high speed. Both
> > you and Samuel implied that this was because it was a USB-2 device.
> > But that is not an adequate answer, because it is perfectly valid for a
> > USB-2 device to run at full speed.
>
> to_usb_device(ddev)->speed really is USB_SPEED_HIGH, otherwise the quirk
> wouldn't work :)

Indeed; I believe you. It's just odd and a little noteworthy, that's
all.

Alan Stern