On Wed, Feb 09, 2011 at 06:26:07PM +0100, Arvid Brodin wrote: > Greg KH wrote: > >On Tue, Feb 08, 2011 at 05:32:50PM +0100, Arvid Brodin wrote: > >>Hi! > >> > >>I get weird problems when I use a null modem cable between the two ports > >>on a FT232BM (2-port FTDI USB-to-serial converter) with an isp1761 host > >>controller. The same thing does not happen with an EHCI host controller. > >>Lengthy details follows: > >> > >>With the EHCI host controller: > >>============================= > >> > >>[Terminal 1] > >>$ cat /dev/ttyUSB1 > >> > >>[Terminal 2] > >>$ echo "Something seems wrong here" > /dev/ttyUSB0 > >>$ echo "Something seems wrong here" > /dev/ttyUSB0 > > > > > >Ick, stop right there, that's your problem. Do not rely on 'cat' and > >'echo' to get the line settings correct at all. Use a serial program > >like minicom to test usb to serial ports properly. > > > >Yes, sometimes you can get cat and echo to work right, if you use stty > >to set up everything properly but note that some usb to serial drivers > >like to reset some of these settings when you close and open the > >connection, making stty pretty much useless for stuff like 'cat' and > >'echo'. > > > >It looks like all of your issues are with the line settings for the > >serial port (line ends, etc.) and should go away if you use minicom. > > > >If your problem persists with minicom or some program like that which > >properly sets the tty settings before transferring the data, please let > >us know. > > > >thanks, > > > >greg k-h > > Ok, thanks for that info! Stupid me to think that basic tools like > cat and echo would work with default line settings. ;) > > Anyway, I did a quick test with microcom (busybox) since that was > all that was available on this embedded system at the moment. > Everything worked fine until I pressed Ctrl-X at which point I got a > kernel panic (null pointer dereference at virtual address 00000014) > at > isp1760_irq+0xde/0x806 (PC) > isp1760_irq+0x248/0x806 (LR) Good, that means there is no tty or usb-serial driver issue, it's just a "normal" isp1760 problem :) thanks for letting us know. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
