> Date: Sat, 6 Jan 2018 22:15:19 +0100 > From: Robert <info...@die-optimisten.net> > > Hi, > > I tried to connect a USB-to-serial cable to a Banana Pi 1 USB port, > but it caused no reaction. No detected device, no kernel or usbdevs > output, nothing. Other USB devices work (so the USB ports seem to > be fine). Same behavior on a Banana Pi M2+. > > The cable is detected on an amd64 and works; I also tested with different > cables and got the same result: > uplcom0 at uhub4 port 6 configuration 1 interface 0 "Prolific Technology Inc. > USB-Serial Controller" rev 1.10/3.00 addr 5 > uplcom0 at uhub4 port 6 configuration 1 interface 0 "Prolific Technology Inc. > USB-Serial Controller" rev 2.00/3.00 addr 5 > uplcom0 at uhub4 port 6 configuration 1 interface 0 "Prolific Technology Inc. > USB-Serial Controller D" rev 1.10/4.00 addr 5 > > I checked the installed arm7 kernel with config; the uplcom device > is enabled. > > Could it be that the Pi does not deliver enough power over USB to > drive the adapter? Though usbdevs on amd64 says it's rather > low-power: > port 6 addr 5: full speed, power 100 mA, config 1, USB-Serial > Controller(0x2303), Prolific Technology Inc.(0x067b), rev 3.00
Power certainly is a common issue for these types of devices, but it is indeed unlikely that this device causes power problems. > Any other ideas? Is it a USB 1.x device? If so, it won't work when directly connected to the USB port of these Allwinner-based devices. Can you try with a USB 2.0 hub in between? The Allwinner SoCs have separate ehci(4) and ohci(4) controllers, but only ehci(4) is enabled right now. I'm not sure what is needed to supoort ohci(4) as well on these ports.
