On Monday 18 June 2007 20:29:42 Antonio Galea wrote: > Quoting Eberhard Fahle <[EMAIL PROTECTED]>: > >> I've compiled the kernel enabling cp2101.ko as a module and loaded it > >> on a Fox; when I plug in the reader, dmesg shows me a few errors > > > > Could you post the errors, please? > > Of course. Here's an excerpt: >... The linux-kernel doc says on usb error-71 ------------------------------------------------------ -EPROTO (*, **) a) bitstuff error b) no response packet received within the prescribed bus turn-around time c) unknown USB error
(*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate hardware problems such as bad devices (including firmware) or cables. (**) This is also one of several codes that different kinds of host controller use to to indicate a transfer has failed because of device disconnect. In the interval before the hub driver starts disconnect processing, devices may receive such fault reports for every request. I can't say what the resason for the failed initialization is, but once I received that "bad cable message" for a device that seemed to work fine on windows, and it turned out using a different cable solved the problem. Also very nice: worn-out usb-sockets ! Whoever came up with these sockets in the usb-spec should be ... doomed for life to do all his backups over this crap piece of hardware. What I wanted to say is "bad cable can happen" please test it. But this is also the error with most unspecified messages. Could be nearly everything. What else : When I plug my tty2USB adapter (FT232) in it sometimes goes through a cycle of up to 5 connect/disconnects before it actually settles and works , but I don't see any error messages during that period of time. I had a look at the usb-developer mailing list, and for your device CP2101 there seems to be no driver support from the manufacturer. Probably one of the reasons, why the device support is marked as "Experimental" in the 2.6.16 kernel. I don't know if the situation changed on newer kernels, in case you can wait for a new foxboard-sdk. If switching to some other hardware (at least my FT232 is working) is an option you might probably want to do this. If you have to stick with the chip, you could enable the usb-debug messages in the kernel options and see if a new fimage with the messages turned on gives some more hints, but i doubt it, sorry. Switch is at kernelconfig->usb-support->USB verbose debug messges (Will eat up memory on your board, switch it of again when you had enough!) > The USB root-hub is required to deliver 500mA on each of the two ports. > I run several devices requesting 500mA without problems. > You could put a self-powered USB-hub, inbetween the foxboard and the > device to test your power-problem theory. If the device would have been disabled for demanding too much power, that would happen on every machine or hub. There is a maximum of 500mA which cannot be circumvented. Eberhard
