(your chances for a quick reply were higher if you used reply-to-all)
On Fri, 14 Apr 2006, Gyorgy Szekely wrote:
> hi,
> i began to use the usb serial console for debugging purposes recenty,
> and ran into the same problems as Guennadi. I followed the thread on
> this list, and applied/tested the patches. Most things work fine now
> (thanks to you), but i still have a few questions.
> Until now we used the first serial port (ttyS0) for debugging.
> Unfortunatelly there's no free serial port in the final product, so we
> decided to give the usb-serial system a try. The devel board had the
> system console (printk's) and a shell on the same serial port (both on
> ttyS0), we'd like to replicate this setup with usb (shell and printk's
> on the same ttyUSB).
> The system console works fine (thanks to you), and opening the device
> /dev/ttyUSB0 for sending additional debug info works too, but we can't
> read from the device. Read blocks and the characters don't arrive. If
> we disable the console support (no printk's, just a shell on ttyUSB0)
> everything's ok, but with the console enabled it becomes output only.
> :(
Heh, so it happened:-) I did see that input didn't work, and thought if I
should try to think about it, but then I decided, since somebody disabled
it, maybe there was a reason for it, and since I don't need it...
Well, I donŠ“t know. Someone might know exactly why it doesn't work and if
it would be easy to make it work. I could have a short look at it, but I
am not an expert in tty / console either. I did wonder about the line
port->tty = NULL;
in usb_console_setup(). Did you try to just leave the original tty in
place and remove the dummy one? No idea what would happen, just
guessing...
Guennadi
> I've checked the code a few times, but i'm too familiar with the
> usb/tty layers, and couldn't come up with a solution. Do you have an
> idea where i should look around?
> The other thing: (not too important)
> The kernel prints the message 'Unable to open an inital console' when
> booting with usb-serial-console, and i can't see the messages from
> init. This happens because the 'device' field is left empty in the
> 'struct console usbcons', so no tty device is associated with the
> console. Would it be possible the register the console with the
> apropriate tty device (ttyUSB0), istead of creating a dummy tty struct
> for the setup? (usb_console_setup())
> This way the usb console would be identical in functionality to the
> standard uart solutuion.
>
> Some info about the system:
> uClinux 2.6.14 (ARM/nommu)
> FTDI chip
---
Guennadi Liakhovetski
