Re: Strange behaviour on PCEngines APU2

[Staffan Thomén <duck%shangtai.net@localhost>]

On 2019-11-20 22:05, Greg Troxel wrote:
> > Normally the tellstick would attach as a uftdi device with an ucom,
> > but because the controlling daemon uses libftdi I've disabled those
> > and it's attached as an ugen device.
> Slightly surprising that the daemon doesn't just use a serial port.
> (aoetec zstick seems to just be serial)

I expect it's because they use the same code for windows.

> > There was also a problem communicating with it when it attached using
> > ehci, disabling ehci made it connect through an uhub attached to xhci
> > and it started to work. Apparently something isn't working right
> > though, but I don't know any knobs to twiddle here.
> Are you sure you didn't get that backwards?  ehci is USB2, and xhci is
> USB3.  Is the tellstick a USB3 device, or USB2, or ?

The tellstick is probably a USB2 device (it's a bit hard to tell..), but 
somehow it still attached and worked on the xhci; this is from the dmesg in 
the first message in this thread:

usb1 at xhci0: USB revision 2.0

uhub1 at usb1: vendor 1022 (0x1022) xHCI Root Hub (0000), class 9/0, rev 
2.00/1.00, addr 0

ugen0 at uhub1 port 1
ugen0: Telldus (0x1781) TellStick Duo (0xc31), rev 2.00/6.00, addr 1

I just tried setting it up on my laptop running 8.1_STABLE from June 10th, and 
it works with either ehci or xhci, but with xhci it only works on one specific 
usb port. If I let it attach via ehci, it works on any of the three ports.

On the lenovo x220:

usb0 at xhci0: USB revision 3.0
usb1 at xhci0: USB revision 2.0

uhub1 at usb1: vendor 1033 (0x1033) xHCI Root Hub (0000), class 9/0, rev 
2.00/1.00, addr 0
uhub1: 2 ports with 2 removable, self powered

ugen0 at uhub1 port 1
ugen0: Telldus (0x1781) TellStick Duo (0cx31), rev 2.00/6.00, addr 1

The man page for xhci indicates that it is for 1.x, 2.0 and 3.0 devices, and 
hints that the xhci driver is for some particular communication method between 
the OS and the controller.

As far as I can tell, the tellstick doesn't cause any issues on the x220 when 
connected via xhci. I tried reading the status from it once a second and 
running a ping at the same time without issue.

> I would be looking at trying to add attachment quirks so that the device
> is not attached by the USB controller that causes problems, which is
> like removing it for this devive, but not in general.

I guess that would be useful if I ever needed the USB ports for anything else.

I've mainly been too busy with work/tired to experiment on the apu2 (also it's 
the main gateway in my network and a pain in the ass if it hangs).

Time willing I will do some tests this weekend.

Staffan