On Mon, 5 Nov 2007, Andrew Greensted wrote: > Hi All, > > I've written a custom device driver based on the usb-skeleton.c file in > the kernel source. > > I want the driver to act in a similar way to when you read from a serial > port. ie, when you do this: > > cat /dev/ttyS0 > > it will wait for data to appear on the port and output to the terminal. > It doesn't timeout, or close the connection when no data is available. > In my case the data source is an IN endpoint from a custom usb board. > > The problem is how do I stop cat (or any other program) closing the > connection when the read function timesout (the condition when no data > is yet available). > > I've tried checking to see if the return value from usb_bulk_msg is > ETIMEDOUT and returning 0 (no bytes read) from my read function rather > than the error, but cat still exits. > > I've also tried setting the timeout parameter in usb_bulk_msg to 0 (wait > forever). But then you can't exit (^c) or even kill the program reading > from the port.
There are two possible approaches. The easy way is just to use a very, very long timeout. Alternatively, when a timeout does occur don't return to the user; instead loop back and submit another usb_bulk_msg. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
