[Buildroot] can not open ttyUSB0
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Wed Jan 30 08:31:12 UTC 2013
Dear Adeel Nafis,
On Wed, 30 Jan 2013 11:27:39 +0500, Adeel Nafis wrote:
> After attaching a 3G Modem USB I am able to successfully use
> 'usb_modeswitch" and get the device to switch with messages indicating
> that the device is connected to /dev/ttyUSB0,1,2. However, after this I
> can not open the /dev/ttyUSBx any more. If i use gnokii for arm it
> prints out some messages indicating that it failed to open the port.
>
> Gnokii output
> GNOKII Version 0.6.26
> Gnokii serial_open: open: No such device <----- the port here is
> set to /dev/ttyUSB0
> Couldn't open ATBUS device: No such device
> Telephone interface init failed: Command failed.
> Quitting.
> Cannot unlock device.
> Command failed.
>
> I have tested the thing out with Ubuntu for arm on the same platform and
> can verify that it works.
Before trying to access the device through /dev, make sure that your
kernel has actually detected this device, and that a driver has been
bound to it:
*) Check your dmesg to see if there is something related to your 3G
modem and the creation of ttyUSB0
*) Check /sys/class/tty/ and check if there is a ttyUSB0 symlink.
Until there is no ttyUSB0 symlink, it means that the kernel hasn't
detected the device, or that a driver is missing for it.
*) Once you have /sys/class/tty/, do a cat /dev/class/tty/ttyUSB0/dev
and check that the major/minor that you see here match the ones you
have used in the static device table (but it seems like 188:0 is
correct for ttyUSB0, so your problem is most likely due to the fact
that the kernel has not detected the device at all).
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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