ftdi-usb-sio-devel

[Ftdi-usb-sio-devel] cannot open port after improper closing

[Paul T. <pth...@gm...>]

I'm using the ftdi_sio driver in the 2.6.28.4 kernel. Sometimes when I
kill an app, I can no longer access /dev/ttyUSB0 (i.e. close never got
called). minicom, my app & more all fail. "more /dev/ttyUSB0" returns
"/dev/ttyUSB0: Input/output error". I don't get any errors in dmesg.
This persists after unloading and reloading the module. The platform
is the AT91RM9200 (an arm9 processor).

Does anyone else see this? Am I missing something small?

thanks,
Paul

Re: [Ftdi-usb-sio-devel] cannot open port after improper closing

[David D. <dav...@ll...>]

Hello,

Something similar sometimes happens to us. My understanding is that the
ftdi output buffer (slave device's side) is full and keeps on being
filled by the HCI or linux usb layers (?), but the slave device doesn't
eat that data. On our design, resetting the slave device does the trick
(it will eat some data at startup, so generally we have to reset it
several times so that it drains completely the linux/hci buffered data
via the ftdi).

I don't know if there is any means to cleanly drain all the buffers
(provided my understanding was right) in software. Any hint would be
welcome.

I might be wrong in my explanation. Please don't hesitate to correct me.
Hope this helps anyway,

Re: [Ftdi-usb-sio-devel] cannot open port after improper closing

[Paul T. <pth...@gm...>]

How do you reset it?

2009/2/13 David Decotigny <dav...@ll...>:
>
> Hello,
>
> Something similar sometimes happens to us. My understanding is that the
> ftdi output buffer (slave device's side) is full and keeps on being
> filled by the HCI or linux usb layers (?), but the slave device doesn't
> eat that data. On our design, resetting the slave device does the trick
> (it will eat some data at startup, so generally we have to reset it
> several times so that it drains completely the linux/hci buffered data
> via the ftdi).
>
> I don't know if there is any means to cleanly drain all the buffers
> (provided my understanding was right) in software. Any hint would be
> welcome.
>
> I might be wrong in my explanation. Please don't hesitate to correct me.
> Hope this helps anyway,
>