On Mon, 9 Jan 2012, Sarah Sharp wrote:
> On Mon, Jan 09, 2012 at 03:24:06PM -0500, Alan Stern wrote:
> > On Mon, 9 Jan 2012, Felipe Balbi wrote:
> >
> > > > Actually it does help: In that situation, the uas driver can print a
> > > > warning message telling the user to plug the device into a different
> > > > controller. We already do something very much like that when a
> > > > high-speed-capable device is plugged into a full-speed controller; see
> > > > check_highspeed() in hub.c. Is there any way to do the same thing when
> > > > a SuperSpeed-capable device is plugged into a USB <= 2.0 controller?
> > >
> > > you should be able to implement something like that by checking your
> > > Device Capability Descriptor which comes with the BOS descriptor set.
> > >
> > > Then you can check wSpeedSuppoted field on that device, if it has the
> > > SuperSpeed bit enabled and you're attached to <=USB_SPEED_HIGH, then you
> > > can warn.
> >
> > Anybody have the time to do this? :-)
>
> Done, although untested. lsusb also needs to be fixed to fetch the BOS
> descriptor if it sees a USB 2.1 device. I'll send that patch shortly.
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index db6b751..1f92ce8 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -3164,6 +3164,16 @@ check_highspeed (struct usb_hub *hub, struct usb_device *udev, int port1)
> kfree(qual);
> }
>
> +static void check_superspeed(struct usb_hub *hub, struct usb_device *udev,
> + int port1)
> +{
> + if (le16_to_cpu(udev->descriptor.bcdUSB) < 0x0300 &&
What's the point of this check? What happens if a USB-3.0 device sets
bcdUSB to 0x0300 in its high-speed device descriptor?
> + dev->bos->ss_cap)
What if dev->bos is NULL?
> + /* BOS descriptor should have already been fetched by now. */
Is this comment really helpful?
> + dev_info(&udev->dev, "not running at top speed; "
> + "connect to a SuperSpeed hub or host\n");
The "or host" part doesn't seem very useful. What if the user doesn't
have a SuperSpeed host? Might as well leave it out.
> +}
> +
> static unsigned
> hub_power_remaining (struct usb_hub *hub)
> {
> @@ -3383,6 +3393,7 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
> && udev->speed == USB_SPEED_FULL
> && highspeed_hubs != 0)
> check_highspeed (hub, udev, port1);
You need to check some things here: Is the device running at less than
SuperSpeed? Are there any USB-3.0 controllers in the system?
Or add those tests to your check_super_speed routine.
> + check_super_speed(hub, udev, port1);
Alan Stern
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