On Mon, 21 May 2007 00:23:42 +0200 Rodolfo Giometti giometti@enneenne.com wrote:
The problem is that the defice __is__ into configured state (USB cable is connected and /dev/ttyUSB0 is running) but nobody has opened the serial line (no minicom/kermit running).
So, I suppose, the above modification is useless...
No, no, unless I'm *really* forgetting my USB enumeration behavior, a device shouldn't go into the configured state unless and until the host does a SET_CONFIGURATION, so the modification would be right since without the USB cable connected the device should be in the DEFAULT state, not the CONFIGURED state.
usb_20.pdf page - 240 Figure 9.1 see ?
Mmm... I see... I supposed to get no control request once device is connected...
Currently I use a timeout of 2ms but I suppose I should decrease it, shouldn't I? :-o
Possibly... I don't think I'd take issue with the specific timeout but, you *can* get a control request at *any* time... including 50% of the way through a DATA IN transfer to the host... there's nothing in the USB specification which precludes control requests on EP0 at *any* time...
You'd probably "get away" with it if you limited your hardware to functioning only with g_serial but, where would be the fun in doing just g_serial ?
Ok, what do you suggest to do? I'm a bit confused... :)
Possibly the simple solution is
#1: Fix it so SET_CONFIGURATION is the only thing to move the device into the configured state.
#2: Either you or I should write a patch then which looks like this.
/* Not tested */ static void __usbtty_puts (const char *str, int len) { int maxlen = usbtty_output.totalsize; int space, n;
/* break str into chunks < buffer size, if needed */ while (len > 0 && device_instance->device_state == STATE_CONFIGURED) { usbtty_poll ();
space = maxlen - usbtty_output.size; /* Empty buffer here, if needed, to ensure space... */ if (space) { write_buffer (&usbtty_output); n = MIN (space, MIN (len, maxlen)); buf_push (&usbtty_output, str, n);
str += n; len -= n; } } }
I think... that *should* work.
Happy Monday.
Bryan