Re: problem with USB-C

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jan 12, 2022 at 10:40:49AM -0500, Alan Stern wrote:
> > >     |__ Port 5: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid,
> > > 1.5M
> > >         ID 04d9:1503 Holtek Semiconductor, Inc. Keyboard
> > >     |__ Port 5: Dev 2, If 1, Class=Human Interface Device, Driver=usbhid,
> > > 1.5M
> > >         ID 04d9:1503 Holtek Semiconductor, Inc. Keyboard
> > >     |__ Port 6: Dev 3, If 0, Class=Human Interface Device, Driver=usbhid,
> > > 1.5M
> > >         ID 30fa:0400
> > > 
> > > 
> > > Why are the hubs listed as Linux Foundation 3.0 root hubs and not 3.1 root
> > > hubs?
> > 
> > Because your devices do not advertise themselves as a USB 3.1 root hub.
> > Perhaps the documentation is incorrect?
> 
> No, that's not it at all.
> 
> The reason why the root hubs for buses 2 and 4 above are both listed as 
> "Linux Foundation 3.0 root hub" is because in hcd.c, the 
> usb31_rh_dev_descriptor and usb3_rh_dev_descriptor structures both set 
> their idProduct values to 0x03, 0x00 (0x0003 in little-endian form).  
> Therefore the hardware database can't distinguish between them.

Ah, right, I totally missed that.  I saw the two different definitions,
but missed the device number.

> One possibility would be for the usb31_rh_dev_descriptor to use 0x04, 
> 0x00 (with the corresponding update to the udev hardware database).  
> Another possibility is for the hardware database entry for product 0x0003
> to be changed simply to "Linux Foundation USB-3 root hub", so that it 
> doesn't specify 3.0, 3.1, or 3.2.

I can do that.  Should only take a few years to trickle out to the
slower distros :)

thanks,

greg k-h