Thanks for taking time to reply!
On Fri, Apr 15, 2011 at 4:09 AM, Greg KH <greg@xxxxxxxxx> wrote:
> On Thu, Apr 14, 2011 at 01:48:46PM +0800, yingchun li wrote:
>> Hi,
>> I have a mobile device, and using USB general serial driver to
>> put some log to PC.
>
> Ick, don't use that driver for any "real" work. What type of device is
> this really? We should use the real driver for it.
In fact, the device is an android device, and there are some gadget function
in it. I need one serial to get log data from modem and send them to PC,and
cannot use the ACM serial (need 3 endpoints)provide by android driver,
for my UDC
only has few endpoints.
>> In user space, there is an APP reading from pipe and writing log data
>> to serial continually.
>> when I start the APP, then insert the usb cable, I can see the
>> log data sent to PC continually.
>> but if I remove the cable, and reconnect it again, the APP is block in
>> the write function, and
>> cannot send data to PC anymore.
>> following is main logic of APP,
>>
>> open pipe,
>> open usb serial(/dev/ttyGS0)
>>
>> for (;;) {
>> read from pipe
>> write to serial(with block mode)
>> if write error (that means receive serial disconnect signal, and
>> write I/O error)
>> close serial
>> open serial again
>> }
>>
>> so, could anyone give me some advice? your any feedback is appreciate.
>
> Are you using the tty interface properly? What happens when your
> application gets the hangup signal?
when the application get hangup signal, now I do nothing. the write operation
will return IO error, and I close the serial and reopen it again, and continue
write, here I think write will blocked and run again when cable connect.
> Does it disconnect and reconnect to
> the new device that shows up when the device is plugged in?
the device name is always /dev/ttyGS0 in gadget mode, in PC, the device
name changed accordingly, sometimes /dev/ttyUSB0, sometimes /dev/ttyUSB1,
and I am sure I connect the plugged device
> thanks,
>
> greg k-h
>
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