On Thu, Dec 22, 2011 at 09:17:06AM -0500, Pris Matic wrote: > Hiya, > > I'm having a really strange issue with a particular device that uses > the FTDI serial chipset. After connection, I'm able to initially open > and communicate with the device no problem. Issues occur when trying > to close the device connection. Some applications are able to close > the device without any issue. In other cases the device seems to > remain open, and attempting to open the device again will result in a > "Device or resource busy" error message. The only way to resolve this > is to physically reconnect the device. From a development standpoint, > issuing a close() on the device fd returns successfully and there > doesn't seem to be any indication that the device should remain in a > 'busy' state. This problem does not occur with another device that > uses a serial chipset by Prolific... in that case, all applications > are able to successfully close the device and re-open it. > > I ran an strace on one application which did close the device > successfully, and one application which did not. I tried to isolate > the relevant information from each trace: > [http://pastebin.com/riJKvCS4]. I'm not too sure what else I can do to > help figure out what's going on and would appreciate any advice. I'm > running Arch Linux, kernel v 3.1.5-1. Those strace outputs look fine, but are you sure that no other program also has opened the port at the same time? If so, all applications need to let it go. If you disconnect the device, all programs that have the port open will get a HANGUP signal, and then they should close the device properly. Have you tried that? And for the "failure" version, does using lsof show any other program that is connected to the device? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
